Hartford weather by month
Hartford runs from about -1°C in January to 24°C in July, with March the wettest month at 207 mm.
warmest month
July
24°C
coolest month
January
-1°C
wettest month
March
207 mm
worst air month
February
14 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -1°C | 170 mm | 146 h | 10 |
| February | 0°C | 45 mm | 226 h | 14 |
| March | 6°C | 207 mm | 235 h | 11 |
| April | 9°C | 138 mm | 245 h | 9 |
| May | 16°C | 105 mm | 303 h | 9 |
| June | 22°C | 88 mm | 352 h | 10 |
| July | 24°C | 126 mm | 342 h | 12 |
| August | 22°C | 109 mm | 327 h | 14 |
| September | 18°C | 25 mm | 274 h | 10 |
| October | 13°C | 15 mm | 296 h | 6 |
| November | 8°C | 57 mm | 222 h | 8 |
| December | 0°C | 100 mm | 192 h | 8 |
About 3,160 hours of sun a year. Roughly 122 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-24. Full method, licences and the list of sources we rejected are on the methodology page.