Rochester weather by month
Rochester runs from about -1°C in January to 23°C in July, with August the wettest month at 184 mm.
warmest month
July
23°C
coolest month
January
-1°C
wettest month
August
184 mm
worst air month
August
11 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -1°C | 107 mm | 79 h | 5 |
| February | 1°C | 50 mm | 215 h | 11 |
| March | 4°C | 63 mm | 216 h | 9 |
| April | 9°C | 127 mm | 225 h | 9 |
| May | 16°C | 63 mm | 346 h | 8 |
| June | 20°C | 88 mm | 311 h | 8 |
| July | 23°C | 109 mm | 384 h | 11 |
| August | 21°C | 184 mm | 315 h | 11 |
| September | 19°C | 101 mm | 312 h | 8 |
| October | 12°C | 54 mm | 258 h | 4 |
| November | 7°C | 81 mm | 184 h | 4 |
| December | 0°C | 83 mm | 99 h | 4 |
About 2,944 hours of sun a year. Roughly 110 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.