Chattanooga weather by month
Chattanooga runs from about 3°C in January to 26°C in July, with September the wettest month at 204 mm.
warmest month
July
26°C
coolest month
January
3°C
wettest month
September
204 mm
worst air month
September
13 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 3°C | 189 mm | 196 h | 9 |
| February | 8°C | 89 mm | 217 h | 10 |
| March | 12°C | 139 mm | 247 h | 9 |
| April | 16°C | 100 mm | 274 h | 8 |
| May | 21°C | 155 mm | 308 h | 7 |
| June | 25°C | 48 mm | 356 h | 10 |
| July | 26°C | 135 mm | 325 h | 11 |
| August | 26°C | 27 mm | 389 h | 11 |
| September | 23°C | 204 mm | 275 h | 13 |
| October | 17°C | 2 mm | 322 h | 6 |
| November | 13°C | 94 mm | 228 h | 8 |
| December | 6°C | 84 mm | 193 h | 10 |
About 3,330 hours of sun a year. Roughly 127 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.