September brings 25°C daytime highs, 84mm of precipitation across about 10 wet days and 12.3 hours of daylight — best for reliable sunshine. The strongest run of the year is July to September. January is the quietest month: cold and snow-focused, and still good for snow, skiing and cabin weekends.
Long-run climate normals for Chicago. Month ratings compare months within Chicago only — they are not a ranking of Chicago against other destinations, and they are not a forecast for a specific year.
Last updated: · Live forecast data refreshes hourly.
| Best month | September — Reliable sunshine |
| Best 3-month window | July–September |
| Quietest month | January — Cold and snow-focused |
| Driest month | February — 49mm |
| Wettest month | May — 106mm |
| Warmest / coolest | July 28°C / February 0°C |
| Seasonality | Strongly seasonal — the months feel like different places |
| Annual rainfall | 940mm over roughly 115 rain days |
January gets roughly 38% less precipitation than September — 52mm against 84mm. That difference, more than temperature, is what changes how a day here feels.
Chicago swings 28°C between July (28°C) and February (0°C) — the month you pick changes what you pack more than where you go.
June gives you 15 hours of daylight against just 9 in December — a 6-hour difference in how much you can actually fit into a day.
February is the driest month at 49mm across roughly 6 wet days, while May peaks at 106mm.
January–December sit at or below freezing, so the precipitation shown for those months falls mainly as snow rather than rain — the millimetre figures are water equivalent, not puddles.
July is almost as good as September, but usually quieter and cheaper. If your dates are flexible, it is the easier trip.
Chicago changes character completely through the year — September and January are effectively two different destinations. Pick the month that matches what you want to do, not the highest-rated one.
Ratings compare months within Chicago, not against destinations worldwide: five stars means the best time to be here, not that Chicago beats anywhere else. Tags describe what the conditions actually suit.
| Month | Rating | High / Low | Precipitation | Wet days | Sun | Daylight | Best for |
|---|---|---|---|---|---|---|---|
| January | ★★☆☆☆ | 0°C / -9°C | 52mm (snow) | 6 | 5h | 9.3h | Snow · Skiing · Cabin weekends |
| February | ★★☆☆☆ | 0°C / -9°C | 49mm (snow) | 6 | 5h | 10.3h | Snow · Skiing · Cabin weekends |
| March | ★★☆☆☆ | 3°C / -5°C | 68mm (snow) | 8 | 5h | 11.7h | Snow · Cabin weekends · Quiet and local |
| April | ★★★☆☆ | 10°C / 1°C | 92mm | 11 | 6h | 13.2h | Spring greenery |
| May | ★★★★☆ | 18°C / 9°C | 106mm | 12 | 4h | 14.4h | Hiking · Cycling · Spring greenery |
| June | ★★★★☆ | 25°C / 15°C | 105mm | 12 | 5h | 15h | All-round conditions |
| July | ★★★★★ | 28°C / 19°C | 101mm | 12 | 11h | 14.7h | Beach days · Swimming |
| August | ★★★★★ | 28°C / 19°C | 101mm | 12 | 11h | 13.7h | Beach days · Swimming |
| September | ★★★★★ | 25°C / 15°C | 84mm | 10 | 11h | 12.3h | Reliable sunshine |
| October | ★★★★☆ | 18°C / 9°C | 82mm | 10 | 6h | 10.8h | Hiking · Cycling · Autumn colour |
| November | ★★★☆☆ | 10°C / 1°C | 79mm | 9 | 6h | 9.6h | Autumn colour · Low-angle light |
| December | ★★☆☆☆ | 3°C / -5°C | 65mm (snow) | 8 | 5h | 9h | Snow · Cabin weekends · Festive season |
| You are planning | Pick | Why |
|---|---|---|
| Sun & beach days | September | 11h daily sunshine, 25°C highs and only 10 rain days. |
| City walking & sightseeing | October | 18°C highs with 10.8h of daylight — long days without heat fatigue. |
| Photography & light | September | 11h of sun and 12.3h daylight give the widest window for golden-hour work. |
| Value & fewer crowds | June | Scores 66/100 — close to peak conditions but outside the busiest window. |
| Cooler-weather travel | October | 18°C highs and 9°C nights suit anyone who dislikes heat. |
Each month in Chicago is described from long-run climate normals and then rated relative to the other eleven months in the same city. A five-star January in a cold destination means January is one of the best times to be there — not that it beats a Mediterranean summer.
| Factor | Weight | What it measures |
|---|---|---|
| Temperature | Described | Average daytime high and overnight low for the month, shown as measured rather than judged. |
| Precipitation | Described | Monthly millimetres and wet-day count, labelled as snow or rain/snow where temperatures make that the likely phase. |
| Sunshine & daylight | Described | Average daily sunshine hours and astronomical daylight length at mid-month, from the city’s latitude. |
| “Best for” tags | Derived | Applied only when the conditions genuinely support the activity — snow depth-friendly cold for skiing, 13–24°C and low rain risk for hiking, dark evenings at high latitude for aurora. A month with few strong use cases gets fewer tags rather than padded ones. |
| Star rating | Relative | Ranks the month against the other eleven months in the same city. Never a comparison between cities. |
Figures are long-run climate averages, not a forecast for a specific year. Where a month lacks sourced rainfall or humidity, the value is modelled from temperature range and rain frequency.
September is the best all-round month in Chicago: 25°C highs, 84mm of precipitation and 12.3 hours of daylight, which suits reliable sunshine. The strongest three-month window is July to September.
January — 0°C highs, 52mm of precipitation over roughly 6 days and 9.3 hours of daylight. It is the cheapest and least crowded time to go, and it still works for snow, skiing and cabin weekends.
February is the driest month at 49mm over about 6 rain days, against 106mm in May. Across the year Chicago records around 940mm.
Yes, but the months are genuinely different trips. September suits reliable sunshine, while January suits snow, skiing and cabin weekends. Pick the month that matches what you want to do.
Daylight ranges from 9 hours in December to 15 hours in June, calculated from the city's latitude.