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Chicago vs Seattle weather: climate comparison
Seattle is the warmer of the two, averaging 52°F (11°C) over the year against 50°F (10°C) in Chicago. Seattle is wetter, with 50.2 in (1275 mm) of precipitation a year to Chicago's 38.7 in (982 mm). Below: every month side by side, from 30 years of ERA5 data (1996–2025).
- Mean temperature
- 10.1°C Chicago
10.9°C Seattle - Annual precipitation
- 982.3 mm Chicago
1274.6 mm Seattle - Rainy days a year
- 121 Chicago
154 Seattle - Sunshine per day
- 8.8 h Chicago
8.3 h Seattle
Month by month
| Month | Chicago | Seattle |
|---|---|---|
| January | -0.9°C | 7.3°C |
| February | 0.6°C | 8.4°C |
| March | 5.4°C | 10.6°C |
| April | 11.4°C | 13.4°C |
| May | 17.9°C | 16.9°C |
| June | 24.2°C | 20.0°C |
| July | 26.6°C | 24.0°C |
| August | 25.8°C | 24.2°C |
| September | 22.5°C | 20.4°C |
| October | 15.6°C | 14.6°C |
| November | 8.3°C | 9.8°C |
| December | 2.2°C | 6.9°C |
Year at a glance
| Measure | Chicago | Seattle |
|---|---|---|
| Mean annual temperature | 10.1°C | 10.9°C |
| Warmest month (avg high) | Jul · 27°C | Aug · 24°C |
| Coldest month (avg low) | Jan · -7°C | Feb · 2°C |
| Annual range (warmest high − coldest low) | 34°C | 22°C |
| Annual precipitation | 982.3 mm | 1274.6 mm |
| Rainy days per year | 121 | 154 |
| Wettest / driest month | May / Feb | Nov / Jul |
| Average sunshine per day | 8.8 h | 8.3 h |
In short: Seattle is the warmest overall (10.9°C mean); Seattle gets the most precipitation (1274.6 mm a year); Chicago is the sunniest (8.8 h a day on average); Seattle has the smallest swing between its warmest and coldest months.
Record high 1996–2025: Chicago 37.4°C (2022-06-21), Seattle 37.9°C (2021-06-28). Record low: Chicago -32.5°C (2019-01-31), Seattle -14.5°C (1996-01-30).
Source: Open-Meteo Historical Weather API (CC BY 4.0). Values are ERA5 reanalysis model data on a ~9–25 km grid, not readings from a weather station, so a single town’s thermometer can differ by a few degrees and local showers can be missed. Monthly means of daily ERA5 values, 1996–2025, for the grid cells nearest Chicago (41.86, -87.65) and Seattle (47.63, -122.32).
Which months differ most?
The gap in average highs is widest in January, when Seattle runs 15°F / 8°C warmer, and narrowest in October (2°F / 1°C apart). The biggest rainfall difference is in November: Seattle gets 5.1 in (130 mm) more on average.
Add a third or fourth city, or swap in any other place, in the full comparison tool. For one city in depth, see the Chicago climate and Seattle climate pages.
Compare Chicago or Seattle with another city
Questions people ask
Is Chicago warmer than Seattle?
Seattle is warmer on average: its mean annual temperature is 52°F (11°C) against 50°F (10°C) in Chicago (ERA5, 1996–2025).
Which gets more rain, Chicago or Seattle?
Seattle, with about 50.2 in (1275 mm) of precipitation a year and 154 days with at least 1 mm, compared with 38.7 in (982 mm) and 121 days in Chicago.
Which is sunnier, Chicago or Seattle?
Chicago averages more sunshine: 8.8 h a day against 8.3 h. Sunshine duration is modelled from cloud cover.
How reliable is this comparison?
Both cities use the same 30-year reanalysis, so differences are consistent. Absolute values describe a grid cell several kilometres wide and can differ by a degree or two from the airport station.