Chicago
United States · North America
Year-round range: 21°F to 80°F
September
Excellent conditions this month
Your monthly fit score
Comfort fit by month.
Climate details▼
Temperature
Average highs and lows.
September has comfortable temperatures — not too hot, not too cold.
Shaded band = typical daily swing (P10 of night lows to P90 of afternoon peaks) — spans wider than avg high/low lines because it captures day-to-day variation.
| = SepPrecipitation
Monthly precipitation, wet-day risk, and snow signal where relevant.
September is one of the wetter months — pack rain gear.
Sunshine
Average hours of bright sun per day.
September is sunny overall, with occasional showers to plan around.
Clear sky
Clear-sky share is the inverse of average cloud cover (100% minus cloud cover). Band labels follow standard meteorological categories; distribution within each band varies by day.
Air comfort by month
Humidity and heat feel by month.
September is mostly comfortable — low heat and humidity pressure.
Time-of-day patterns
Typical hourly rhythm for September.
Temperature by hour
Temperature by hour and month
Typical temperature through the day across the year (1996-2025 normals, local time). Shaded cells are nighttime.
In September, afternoons reach about 72° and nights settle near 60°.
▶Full month-by-month data
| Month | High °F | Low °F | Rain days | Rain (in) | Sun h/day | Humidity |
|---|---|---|---|---|---|---|
| Jan | 31°F | 21°F | 7 | 2.4in | 3.5h | 74.71428571428571% |
| Feb | 34°F | 22°F | 7 | 2.1in | 4.7h | 73.99999999999999% |
| Mar | 42°F | 30°F | 8 | 2.8in | 5.5h | 72.85714285714285% |
| Apr | 53°F | 40°F | 12 | 4.0in | 6.4h | 71.85714285714286% |
| May | 64°F | 52°F | 15 | 4.6in | 7.5h | 73.14285714285714% |
| Jun | 75°F | 63°F | 13 | 4.5in | 8.5h | 72% |
| Jul | 80°F | 69°F | 12 | 3.9in | 9.3h | 71.28571428571428% |
| Aug | 79°F | 68°F | 13 | 3.9in | 8.8h | 72% |
| Sep | 73°F | 61°F | 11 | 3.2in | 8h | 69.85714285714286% |
| Oct | 61°F | 50°F | 12 | 3.8in | 6.1h | 68.71428571428571% |
| Nov | 47°F | 38°F | 8 | 2.7in | 4.5h | 70.42857142857143% |
| Dec | 37°F | 28°F | 7 | 2.4in | 3.4h | 74.57142857142856% |