Today's barometric pressure in Chicago, a 48-hour pressure chart, and a risk score for weather-triggered migraine and headache, based on pressure drops, humidity, and temperature changes.
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Chicago's position on Lake Michigan makes it one of the most barometrically volatile cities in the US. Cold fronts sweep across the plains and collide with lake-effect moisture, creating rapid pressure changes that migraine sufferers feel acutely.
Worst season for migraines: October through May. Chicago sits where Arctic air masses collide with warm Gulf moisture, creating some of the sharpest frontal contrasts in the country. Late fall through March brings the most frequent pressure drops, peaking in March, when 62% of days see a 5 hPa drop, while summer is far calmer, at 26% of days or fewer.
Common triggers in Chicago: lake-effect pressure systems, rapid cold front passages, extreme wind chill creating vascular stress. Lake Michigan moderates temperatures near the shore but creates its own weather patterns. The lake generates pressure differentials between the waterfront and inland neighborhoods, meaning migraine sufferers in different parts of the metro can experience different trigger levels on the same day.
Typical pressure: Chicago averages 995 hPa at rest, measured at the city's own elevation rather than corrected to sea level, and storm systems can push readings down to 978 hPa. Swings of 7-17 hPa over 24 hours are common during active weather and fall within the range most associated with pressure-triggered migraines.
2026 index: Chicago ranks #23 of 100 in our 2026 U.S. Migraine Risk Index, where #1 is the most challenging city for weather-driven migraine.
Can Chicago weather trigger migraines?
Yes. Chicago experiences 7-17 hPa barometric pressure swings, and research shows pressure drops are one of the most common migraine triggers. The city's specific patterns include lake-effect pressure systems, rapid cold front passages, extreme wind chill creating vascular stress.
What time of year are migraines worst in Chicago?
In Chicago the most barometrically volatile stretch of the year falls in October through May. That is when weather is most likely to play a part, if weather is a trigger for you at all. See when migraine weather season starts across the U.S.
Is there a barometric pressure headache forecast for Chicago?
This page works as one. Many people call a headache that arrives with a weather change a barometric pressure headache, and this forecast tracks the pressure drops, humidity and temperature swings behind that idea. The score covers the next 24 hours in Chicago and the chart shows the next 48. It is built on migraine research, so treat it as a rough guide for other headaches. A sudden, severe headache needs urgent medical care, whatever the weather.
Your own forecast
This page shows the weather risk for everyone in Chicago. The MigrAid app learns yours. It saves the barometric pressure, humidity and temperature with every migraine you log, shows whether Chicago's swings really line up with your attacks, and alerts you when conditions match your own trigger history.