Juneau weather by month
Juneau runs from about -3°C in January to 15°C in August, with July the wettest month at 473 mm.
warmest month
August
15°C
coolest month
January
-3°C
wettest month
July
473 mm
worst air month
July
6 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -3°C | 356 mm | 55 h | 1 |
| February | -2°C | 138 mm | 133 h | 2 |
| March | 0°C | 177 mm | 191 h | 3 |
| April | 3°C | 161 mm | 262 h | 4 |
| May | 7°C | 235 mm | 216 h | 4 |
| June | 13°C | 73 mm | 313 h | 6 |
| July | 14°C | 473 mm | 155 h | 6 |
| August | 15°C | 280 mm | 297 h | 5 |
| September | 10°C | 430 mm | 146 h | 3 |
| October | 5°C | 444 mm | 113 h | 2 |
| November | -1°C | 178 mm | 94 h | 1 |
| December | 0°C | 334 mm | 38 h | 1 |
About 2,013 hours of sun a year. Roughly 275 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 2026-05-27. Full method, licences and the list of sources we rejected are on the methodology page.