Updated 10 October 2026
At a glance
- A 2022 meta-analysis of 20 studies on inflammatory bowel disease found a significant correlation between exacerbation and seasonal variation, and in Crohn's disease three studies (n = 1597) gave a pooled estimate of 0.12.
- A temperature study linked short-term changes toward very cold or very hot weather with acute exacerbation of inflammatory bowel disease, with the association confined to the cold and hot ranges of temperature.
- A table of the studies, a flare and weather record, a word list, four steps and a one-page summary follow below.
- Crohn's Journey holds flare days, weather notes and other events in one dated history, and its Doctor Report turns that history into a one-page summary for the gastroenterology visit.
Many people with Crohn's disease wonder whether the weather has anything to do with a flare. A few studies have looked at seasons and temperature, and what they found is more modest than the question suggests, and mostly about inflammatory bowel disease as a whole.
Here is what a meta-analysis, a temperature study, a diagnosis-season study and NIDDK report, then a table, a flare and weather record, a word list, four steps and a one-page summary for the visit.
What a meta-analysis, a temperature study, a diagnosis-season study and NIDDK report about Crohn's disease flares and the seasons
A 2022 systematic review and meta-analysis searched 7,346 publications and selected 20 studies on temperature, weather, seasons, atmosphere and climate in inflammatory bowel disease. Its conclusion: "There was a significant correlation between IBD exacerbation and seasonal variations, however, it was difficult to synthesize pooled results of other environmental indicators due to the small number of studies and the various types of reported outcome measures." For Crohn's disease specifically, "three studies, n = 1597" gave a pooled estimate of 0.12 (95% CI 0.07-0.18). (Source: journals.plos.org.) In the discussion the authors write that "it seems that IBD exacerbation tended to occur slightly more frequently in warmer seasons," and that "it is difficult to obtain conclusive results by generalizing seasonality and IBD exacerbation."
The review also notes that "the countries and cities in all 20 published studies were located above the Tropic of Cancer in the Northern Hemisphere," so the findings say little about other climates. (Source: journals.plos.org.)
A 2023 case-crossover study used nationwide claims data from South Korea, validated against a United Kingdom cohort, and reported "significant associations between acute exacerbation of IBD and the short-term ambient temperature changes toward severe temperatures," in the cold (odds ratio 1.13) and hot (odds ratio 1.16) ranges, adding that "the association was not significant in the moderate weather." It covers inflammatory bowel disease as a group, and it does not separate Crohn's disease.
A 10-year observational study in China of 2038 patients with Crohn's disease at diagnosis found that "the diagnosis occurred more frequently in summer and less frequently in winter." That concerns the timing of diagnosis rather than flares.
NIDDK says: "Experts think a person's environment, the place where someone lives, the conditions in which they live, and factors outside their body, may play a role in causing Crohn's disease," and its facts page states: "When people have symptoms, it's called a flare."
Taken together, the studies report modest, mostly group-level patterns, and none says what the weather will do for one person. Your own dated record of flares and conditions is the part only you can add.
Flare days and a short weather line can go into the Flare Tracker and Daily check-in of Crohn's Journey (by Health Journey Labs), each on its own date.
A table of weather studies on Crohn's: focus, population, and kind of finding
The five sources study different questions, and lining them up shows how far each reaches.
Table of studies on seasons, temperature and flares
Crohn's Journey reviewed what each weather study examined and what kind of finding it reports.
| Source | What it examined | Who | Kind of finding |
|---|---|---|---|
| 2022 meta-analysis | Seasons, temperature, atmosphere and exacerbation | 20 studies of inflammatory bowel disease; Crohn's subgroup of 3 studies, n = 1597 | Significant correlation with season; pooled estimate 0.12 for Crohn's; authors urge caution |
| 2023 case-crossover study | Short-term temperature change and acute exacerbation | Inflammatory bowel disease, Korean claims data, UK validation | Associations toward cold and hot extremes; none in moderate weather |
| 10-year observational study | Season of diagnosis | 2038 patients with Crohn's disease in China | Diagnosis more frequent in summer, less in winter |
| NIDDK symptoms and causes | Possible causes | Crohn's disease | Environment may play a role in causing it |
| NIDDK definition and facts | What a flare is | Crohn's disease | Symptoms present is called a flare |
Only the second row speaks to temperature in the short term, and only the first separates Crohn's disease from the broader group. The third concerns when people were diagnosed, which is a different event from a flare. The table therefore cannot say that weather causes flares for any individual, and none of the sources claims it. The guide to Crohn's triggers in food, stress, sleep and weather compares weather with the other things people track.
Entries in Crohn's Journey keep a flare date and the weather note on one line, so a clinician can read both without searching.
A flare and weather record with Crohn's: dates, symptoms, conditions, other events
Weather is one of many things that can change in a week, so a record that holds several side by side is the honest companion to these studies. Every row below is made up, there to show the columns.
Record your flares, symptoms, weather and events
Crohn's Journey keeps flare, symptom and weather notes on the same dated row.
| Date | Flare or usual day | Symptoms | Weather note | Other events that week |
|---|---|---|---|---|
| 4 Feb | Flare day | Cramping, urgent stools | Cold spell, sharp drop | Stomach bug in the house |
| 5 Feb | Flare day | Fatigue, loose stools | Still cold | Poor sleep |
| 18 Apr | Usual day | Mild bloating | Mild and steady | Busy week at work |
| 20 Jul | Flare day | Cramping | Heat wave | Travel, unfamiliar food |
Keep the weather note short and plain: cold spell, heat wave, sharp change, mild and steady. Leave it blank if you did not notice. The other-events column matters just as much, because the studies cannot separate weather from infections, travel, stress or sleep, and a clinician reading your rows will want to see them together.
After a few months the record may show nothing special about weather for you, or it may show a pattern worth raising. Either result is useful, and neither is a conclusion. The guide to what to log between Crohn's flares covers what else belongs on the page.
A row from the record can become an entry in the Daily Journal of Crohn's Journey, with the weather line in your own words.
Words about Crohn's flares, weather, and other changes that week
Clinicians ask about symptoms first and context second, so a few plain words for each keep the conversation on track.
Checklist of flare, symptom, weather and context words
These are the flare and weather words Crohn's Journey uses in its record.
- Flare words: flare day, usual day, started on, settled by, still going.
- Symptom words: cramping, urgent stools, loose stools, blood noticed, fatigue, fever.
- Weather words: cold spell, heat wave, sharp change, mild and steady, did not notice.
- Context words: stomach bug nearby, travel, new food, poor sleep, stressful week.
- Question words: is there a pattern, what else should I record, who to contact.
Pick the words that fit each day and add the date. NIDDK describes a flare as the time when people have symptoms, and writing the start and end dates of each flare gives the clinician the length of it. These words describe what happened and make no claim about causes. Heavy bleeding, fever with severe pain, or any urgent symptom is a reason to contact your clinician or your local emergency number first, and the notes can wait.
The context words you choose can be saved in the Daily Journal of Crohn's Journey, as you would say them to the clinician.
Four steps with Crohn's before a visit about weather and flares
If weather has been on your mind, a few steps turn the hunch into something the clinician can look at. They put dates in order and add nothing else.
Prepare your flare and weather record before the visit
Before the visit, Crohn's Journey condenses the flare and weather record.
- List your flare days from the last few months, with start and end dates.
- Add a short weather line for each, or leave it blank if you did not notice.
- Add the other events of each week: infections nearby, travel, sleep, stress.
- Pick two or three questions, with the clearest first.
From Crohn's Journey, we recommend reading the record through the evening before the visit (Crohn's Journey checklist), so the pattern, or its absence, is clear in your mind.
Questions can be plain, such as whether the clinic sees a pattern in the dates (the guide to rebuilding the story after being dismissed before Crohn's was named helps with an earlier history), what else it would like recorded and how to reach the team during a flare. The studies cannot answer these, and the clinic can.
During the visit, write each reply beside its question and add a date for any follow-up. If the clinic wants a particular item recorded, add the start date so the next record begins from it.
Questions about patterns can wait in My Care Team within Crohn's Journey, filed under the gastroenterology clinician.
A one-page Crohn's summary: flare dates, weather lines, other events, questions
A single page shows the clinician your flares in order with the context beside each, and the daily entries stay behind it.
One-page summary of flare dates, events and questions
Crohn's Journey fits flare dates, events and questions on one page.
- Each flare, with start and end dates.
- The weather line for each, where you noted one.
- Other events in the same weeks.
- Any flare-free stretches, in a line.
- What has been seen or done, with dates.
- Two or three questions for this visit.
Hand the page over as the visit opens and offer to go through it together, and enter whatever the clinician suggests with the date of the visit.
The page records dates and conditions. Whether weather matters for you, and what follows, is for your clinician to decide with the full picture, and no study, page or app decides it. Something urgent is a reason to call your local emergency number before using the page.
Crohn's Journey produces this page through its Doctor Report, and the daily entries remain behind it.
How Crohn's Journey can help
A calendar with a few notes is a fine start. If you want flare days, weather lines and other events held together, the best Crohn's disease apps guide compares the options.
Crohn's Journey is a personal crohns tracker from Health Journey Labs on the App Store and Google Play. The studies report modest group patterns, and a dated record shows a clinician what your own weeks looked like. Whether weather matters for your flares is a question for your gastroenterology team, and the page carries the dates and conditions into that conversation. Below is what you can use and how each part helps.
- Stool Tracker (Bristol Scale) — Logs stool form (Bristol Scale), urgency or bathroom load, short marks; read together with pain, meals, energy.
- Food Tracker — Logs meal or drink lines; read together with pain, urgency, energy, stool, sleep.
- Flare Tracker — Logs flag a day clearly worse than the usual hard week, onset, intensity, short note; read together with history across weeks (one-off spike vs repeating pattern).
- Daily check-in — Logs physical symptoms, emotional state, nutrition, sleep, exercise, meds, external factors; read together with the rest of the logged history.
- Daily Journal — Logs free-text notes, voice entry; app-specific items: what the day limited, bathroom maps, partner talks, visit debriefs, leftover guilt after you canceled; read together with scores and other logged history (adds context).
- Weight Tracker — Logs scale or body notes, weight loss, nutrition or clinic weigh-ins when watched with a clinician; read together with stool, meals, energy, sleep.
- My Meds — Logs medicine names, timing, dose; app-specific items: biologics, steroids, other options you actually use; read together with stool weeks, pain, sleep, the rest of the tracked history.
- My Labs — Logs result dates; app-specific items: blood counts, stool tests, calprotectin, imaging, other tests; read together with symptoms, function.
- Weekly Goals — Logs one small aim, whether it held; read together with real check-ins.
- Learn — Logs short education topics, prompts; app-specific items: flares, pacing, bathroom load, visit prep; read together with your own logged weeks.
- AI companions — Logs Clara (general chat), specialist companions; app-specific items: knowledge, fitness, nutrition, relationships; read together with your logged history (companions already see it); used for: visit wording; a calm partner script; a soft rain-check line; a listening ear after a hard bathroom day.
- My Assessments — Logs structured check-ins beyond daily scores, onboarding life and social context; read together with ongoing history.
- My Care Team — Logs clinicians, short visit notes; app-specific items: tends to ask mainly about stool count rather than function; read together with logged history; used for: visit prep (what to ask and bring); notes during the visit; review afterward.
- Doctor Report — Logs one-page summary exported from logged history; app-specific items: dates, stool and meal context, symptoms, how you functioned; read together with the history already logged.
- Period Tracker — Logs start and stop dates, flow, how heavy or light bleeding felt; read together with pain, stool, energy, everything else logged.
Everything you log builds one history, and insights get stronger as it grows. Custom symptoms let you add your own labels.
We make Crohn's Journey at Health Journey Labs. This guide is educational and does not replace medical advice. Diagnosis, medication decisions, and urgent care decisions belong with your treating clinicians.
Sources
- PLOS ONE: effects of temperature, weather, seasons, atmosphere and climate on the exacerbation of inflammatory bowel diseases, a systematic review and meta-analysis
- PLOS ONE: ambient temperature and acute exacerbation of inflammatory bowel disease
- Frontiers in Medicine: seasonal variations of Crohn's disease at diagnosis, a 10-year observational study in China
- NIDDK: symptoms and causes of Crohn's disease
- NIDDK: definition and facts for Crohn's disease
FAQ
The answers below draw on the sources cited in this guide, and the app they mention is Crohn's Journey (by Health Journey Labs).
Does weather cause Crohn's disease flares?
A 2022 meta-analysis found a significant correlation between seasonal variation and inflammatory bowel disease exacerbation, and its authors urge cautious interpretation. No source here says weather causes flares in any one person.
A flare and weather record kept in Crohn's Journey shows a clinician what your own weeks looked like, which is a different thing from what a group-level correlation can show, and it stays on its dates.
What did the meta-analysis find for Crohn's disease?
For Crohn's disease, three studies with 1597 people gave a pooled estimate of 0.12 for seasonal variation and exacerbation. The review says it was difficult to obtain conclusive results by generalizing seasonality across studies.
The published numbers can be read at the clinic if you wish, and your own dated flare days in Crohn's Journey give the clinician the local picture to hold beside them during the conversation.
Do flares happen more in summer or winter?
The meta-analysis authors write that exacerbation tended to occur slightly more frequently in warmer seasons, while noting that conclusions are difficult to generalize. A study of diagnosis timing found diagnosis more often in summer.
Noting the month of each flare in Crohn's Journey lets you and the clinician see whether your flares cluster, and the season is a column you can skip if nothing stands out in your own history.
What did the temperature study report?
A case-crossover study of inflammatory bowel disease reported associations between acute exacerbation and short-term temperature changes toward severe cold or heat, and found no significant association in moderate weather conditions overall.
A short weather line beside each flare in Crohn's Journey lets the clinician see whether your flares followed a sharp change, and a blank line simply says nothing registered with you that week.
Is that study about Crohn's disease only?
It covers inflammatory bowel disease as a group, which includes Crohn's disease and ulcerative colitis, and the abstract reports the group as a whole. Ask your clinician how it applies to you.
Writing your diagnosis and the type of flare in your Crohn's Journey entries keeps your own record specific, whatever group a study covers, and the clinician reads those specifics first, before any published figure.
Does diagnosis in summer mean anything for flares?
The 10-year study in China reported that diagnosis occurred more often in summer and less often in winter, which concerns when people were diagnosed. A diagnosis is a different event from a flare, and the study is about the former.
Keeping the date of diagnosis as one entry and each flare as another in Crohn's Journey stops the two kinds of event from being mixed up when you read your history back later.
What does NIDDK say about environment?
NIDDK says experts think a person's environment, including the place where someone lives and factors outside their body, may play a role in causing Crohn's disease. The page gives no weather figures and no season data.
Where you were living or traveling during each flare, noted in Crohn's Journey, gives the clinician the place information NIDDK mentions without any interpretation from you, and the clinician decides what, if anything, it means.
How should I describe the weather in my notes?
Plain words work: cold spell, heat wave, sharp change, mild and steady. Leave the line blank on days when nothing registered, since an invented weather line is worse than none at all.
In Crohn's Journey the weather line sits inside the same dated entry as the flare, so a clinician reading a month of entries sees both together without turning pages or comparing separate lists.
What else should go beside the weather?
Infections in the household, travel, new foods, sleep and stressful weeks are all worth a line, because the studies cannot separate weather from them. The clinician can weigh them together with the flare dates.
Adding those events as short lines in the Daily Journal of Crohn's Journey keeps them on the same dates as the flare entries, so patterns across them are easy to see at a glance.
What should I take to the gastroenterology visit?
Bring your record, the one-page summary and two or three questions. A single page reads quickly in a short appointment, and the daily entries behind it cover any date the clinician happens to ask about.
Your page from the Doctor Report in Crohn's Journey is assembled from your entries before you leave, and nothing needs retyping when a specific week comes up in the room during the visit.
Can an AI chat tell me whether weather affects my Crohn's disease?
Weighing that takes a clinician with your history, and urgent symptoms call for your clinician or your local emergency number first. An AI chat can help tidy notes and word questions, and that is where its role ends.
The in-app companion in Crohn's Journey can recap flare days and weather lines in a few sentences, each traceable to an entry you made, and the reading of them stays with your clinician.
How long should I keep a weather record?
No source here sets a period, so the clinic's preference decides. Several months covering both flares and flare-free stretches is a common size for a record, though the clinic may want more or less than that.
A weekly goal in Crohn's Journey, such as adding the week's weather line each Sunday, keeps the run going, and a gap in the record simply reads as a gap with no explanation needed.
Who might need the page?
A gastroenterologist, a primary care clinician and an IBD nurse may each hold part of the picture, and one shared page keeps each of them reading the same dates and the same weather lines.
Passing the same export from Crohn's Journey to each of them keeps everyone on the same dates, and the export date shows which copy is newest when pages are compared later on.
When is a symptom urgent?
Heavy bleeding, fever with severe pain, or any other urgent symptom is a reason to contact your clinician or your local emergency number straight away. The record supports planned visits and comes second to that.
With the urgent situation dealt with, Crohn's Journey is where the date and what happened can go, so the next visit opens with an account written close to the event itself.
Should I worry about privacy when I track symptoms?
Bathroom counts, stool notes and urgency details are among the most private entries anyone keeps. Use a passcode, avoid shared computers, and print only the summary rows your gastroenterology team needs for the visit.
In Crohn's Journey, the entries are your own health notes. The app's privacy policy explains how data is stored and handled, so read it before you add sensitive details. This article is general information and not medical advice.