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Boston vs Chicago weather: climate comparison
Boston is the warmer of the two, averaging 51°F (11°C) over the year against 50°F (10°C) in Chicago. Boston is wetter, with 45.4 in (1154 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
- 10.6°C Boston
10.1°C Chicago - Annual precipitation
- 1154.0 mm Boston
982.3 mm Chicago - Rainy days a year
- 121 Boston
121 Chicago - Sunshine per day
- 8.6 h Boston
8.8 h Chicago
Month by month
| Month | Boston | Chicago |
|---|---|---|
| January | 1.9°C | -0.9°C |
| February | 3.5°C | 0.6°C |
| March | 7.5°C | 5.4°C |
| April | 13.5°C | 11.4°C |
| May | 19.1°C | 17.9°C |
| June | 24.4°C | 24.2°C |
| July | 27.9°C | 26.6°C |
| August | 26.9°C | 25.8°C |
| September | 22.9°C | 22.5°C |
| October | 16.5°C | 15.6°C |
| November | 10.2°C | 8.3°C |
| December | 5.0°C | 2.2°C |
Year at a glance
| Measure | Boston | Chicago |
|---|---|---|
| Mean annual temperature | 10.6°C | 10.1°C |
| Warmest month (avg high) | Jul · 28°C | Jul · 27°C |
| Coldest month (avg low) | Jan · -7°C | Jan · -7°C |
| Annual range (warmest high − coldest low) | 34°C | 34°C |
| Annual precipitation | 1154.0 mm | 982.3 mm |
| Rainy days per year | 121 | 121 |
| Wettest / driest month | Mar / Feb | May / Feb |
| Average sunshine per day | 8.6 h | 8.8 h |
In short: Boston is the warmest overall (10.6°C mean); Boston gets the most precipitation (1154.0 mm a year); Chicago is the sunniest (8.8 h a day on average); Chicago has the smallest swing between its warmest and coldest months.
Record high 1996–2025: Boston 40.3°C (2011-07-22), Chicago 37.4°C (2022-06-21). Record low: Boston -26.4°C (2016-02-14), Chicago -32.5°C (2019-01-31).
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 Boston (42.36, -71.13) and Chicago (41.86, -87.65).
Which months differ most?
The gap in average highs is widest in February, when Boston runs 5°F / 3°C warmer, and narrowest in June (0°F / 0°C apart). The biggest rainfall difference is in December: Boston gets 2.0 in (50 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 Boston climate and Chicago climate pages.
Compare Boston or Chicago with another city
Questions people ask
Is Boston warmer than Chicago?
Boston is warmer on average: its mean annual temperature is 51°F (11°C) against 50°F (10°C) in Chicago (ERA5, 1996–2025).
Which gets more rain, Boston or Chicago?
Boston, with about 45.4 in (1154 mm) of precipitation a year and 121 days with at least 1 mm, compared with 38.7 in (982 mm) and 121 days in Chicago.
Which is sunnier, Boston or Chicago?
Chicago averages more sunshine: 8.8 h a day against 8.6 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.