Weather risk for filming in Chicago
Chicago averages 14 rain days in April — a three-day exterior shoot then hits at least one with 85 % probability. In February (8 rain days) the same risk drops to 61 %. The calculator above is preset to Chicago and runs the numbers for your count of exterior days.
Weather risk calculator for Chicago
- Risk per day
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- At least one day hit
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- Expected lost days
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Rain risk in Chicago by month
Rain days are long-term monthly means — not a forecast, but the basis for the budget question: once the chance of losing a day passes ~60 %, the cover set is cheaper than the loss.
| Month | Rain days | Mean temp | Sun hours/day | Risk (3 days) |
|---|---|---|---|---|
| January | 10 | -3.3 °C | 4.9 | 70 % |
| February | 8 | -2.3 °C | 6.8 | 61 % |
| March | 11 | 3.0 °C | 7.8 | 75 % |
| April | 14 | 8.0 °C | 8.8 | 85 % |
| May | 13 | 14.3 °C | 10.1 | 82 % |
| June | 13 | 20.4 °C | 11.7 | 82 % |
| July | 12 | 22.8 °C | 11.9 | 78 % |
| August | 12 | 22.6 °C | 11.5 | 78 % |
| September | 10 | 19.9 °C | 9.7 | 70 % |
| October | 12 | 12.8 °C | 7.5 | 78 % |
| November | 8 | 5.5 °C | 6.0 | 61 % |
| December | 10 | 0.6 °C | 5.0 | 70 % |
The best month for exteriors
Combining daylight and rain days, July comes out ahead in Chicago: 14h 56min of usable light against 12 mean rain days. The driest month (February) and the brightest are not automatically the same — which is exactly why the combined view matters.
For scheduling, a weather day costs more than the day itself: location availability, crew follow-on bookings and possibly the travel home. TillyGen puts the month's rain risk right next to the sun window inside the schedule — together they decide which day can happen outside.
Frequently asked
When does it rain least in Chicago?
February, with a mean of 8 rain days. The most falls in April with 14.
How is the washout risk computed?
Rain days ÷ 30 gives the per-day hit probability; across N exterior days, 1 − (1 − p)ᴺ is the chance of at least one hit. Deliberately simple and conservative — it prices the month's structural risk rather than forecasting weather.
What is the best month to shoot in Chicago?
On light and rain combined, July. The matching sun times live on the golden-hour page for Chicago and on the city page.