Chicago, IL restaurant weather by month
| Month | Avg high | Avg low | Rainy days | Muggy days | Patio-friendly days |
|---|---|---|---|---|---|
| January | 32° | 20° | 6 | 0 | 0 |
| February | 38° | 22° | 5 | 0 | 1 |
| March | 49° | 33° | 8 | 0 | 1 |
| April | 58° | 40° | 8 | 0 | 6 |
| May | 71° | 52° | 8 | 4 | 13 |
| June | 82° | 63° | 7 | 12 | 17 |
| July | 84° | 68° | 7 | 21 | 17 |
| August | 83° | 66° | 6 | 18 | 19 |
| September | 78° | 61° | 5 | 9 | 20 |
| October | 64° | 48° | 7 | 2 | 10 |
| November | 49° | 35° | 5 | 0 | 2 |
| December | 38° | 25° | 5 | 0 | 0 |
Averages of daily observations at O'Hare Airport (ORD), 2016–2025. Rainy day: 0.10″ of rain or more. Muggy day: dew point reached 65°F or higher. Patio-friendly day: high between 65°F and 88°F, less than 0.05″ of rain, and average wind under about 14 mph. Highlighted rows are the three best patio months. Your neighborhood can differ from the airport, especially near water or downtown.
What it means for your restaurant
- Plan your patio season for May–September. Those months average 12 or more patio-friendly days. Outside that window, treat outdoor seating as a bonus you open on good days rather than a fixed part of your floor.
- Get ready for the jump into May. Patio-friendly days rise by about 8 from April to May — the biggest month-to-month change of the year. Have patio furniture, staffing and outdoor menus ready before the first warm stretch, not after it.
- March is the wettest month, averaging about 8 days with 0.1″ or more of rain. That’s the month to have a takeout and delivery push ready to go, and to keep an on-call shift you can release if a storm hits at dinner.
- Humidity matters as much as temperature in July. About 21 days that month reach a dew point of 65°F or higher, when it feels sticky even at moderate temperatures. Guests will drift indoors faster than the thermometer suggests.
- Winter is about the commute, not the patio. January averages a high of only 32°F. Snow, ice and wind chill keep guests home more than plain cold does — the forecast discussion will tell you when a storm is coming and how confident forecasters are.
Where Chicago forecasts come from
Chicago is covered by the National Weather Service forecast office LOT. Several times a day, its forecasters publish an Area Forecast Discussion — a plain-text explanation of what they expect, when, and how confident they are. It’s the most useful forecast product most restaurant managers have never read. Our guide on how to read a forecast discussion walks through it, and GuestFlow Weather reads it for you every morning.
Averages tell you what to plan for this season. What you need each morning is what today will do — and that’s where a daily briefing helps. For the bigger picture, see how rain affects restaurant traffic and the best weather for patio dining.