Climate averages 1991–2020
Oslo weather
in September.
A mild, moderately wet month: the 5th warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a mild month in Oslo: daytime highs average 15.5°C and nights cool to about 9.5°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 89 mm of rain on roughly 11 days, which makes September a moderately wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 57 min on an average September day.
The nearest other city in this atlas is Lillestrøm (18 km away). In September its highs average 15.0°C, 0.5°C cooler than Oslo, with 81 mm of rain.
Among the 8 cities listed in Norway, Oslo ranks 3rd of 8 for the warmest September highs and 3rd of 8 for the driest September (rainfall, lowest first). The mean September high of those 8 cities is 15.0°C; Oslo is 0.5°C warmer than that mean.
From September to October, average highs fall by 6.5°C to 9.0°C, and monthly rainfall rises from 89 mm to 94 mm.
The annual picture
September in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Oslo climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.9°C-6.8°C | -6.8°C | 72 | 10.9 | 6.87 h |
| February | -0.4°C-6.4°C | -6.4°C | 52 | 8.6 | 9.19 h |
| March | 4.0°C-3.3°C | -3.3°C | 54 | 8.2 | 11.812 h |
| April | 9.8°C1.1°C | 1.1°C | 55 | 9.1 | 14.515 h |
| May | 15.7°C6.4°C | 6.4°C | 77 | 11.4 | 17.117 h |
| June | 19.4°C10.9°C | 10.9°C | 95 | 12.3 | 18.719 h |
| July | 21.6°C13.9°C | 13.9°C | 100 | 12.6 | 18.018 h |
| August | 20.2°C13.2°C | 13.2°C | 112 | 14.2 | 15.616 h |
| September, selected | 15.5°C9.5°C | 9.5°C | 89 | 10.8 | 12.913 h |
| October | 9.0°C4.6°C | 4.6°C | 94 | 11.7 | 10.210 h |
| November | 3.8°C0.3°C | 0.3°C | 92 | 12.0 | 7.68 h |
| December | -0.5°C-4.8°C | -4.8°C | 71 | 11.1 | 6.16 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Lillestrøm in SeptemberNorway · 18 kmHigh 15.0°C · Low 8.6°C · 81 mm rain
- Drammen in SeptemberNorway · 36 kmHigh 15.8°C · Low 9.7°C · 94 mm rain
- Fredrikstad in SeptemberNorway · 78 kmHigh 15.6°C · Low 10.6°C · 81 mm rain
- Kristiansand in SeptemberNorway · 252 kmHigh 15.4°C · Low 10.7°C · 127 mm rain
- Gothenburg in SeptemberSweden · 255 kmHigh 16.2°C · Low 10.6°C · 93 mm rain
- Örebro in SeptemberSweden · 261 kmHigh 15.6°C · Low 9.4°C · 55 mm rain
- Borås in SeptemberSweden · 274 kmHigh 15.5°C · Low 9.7°C · 83 mm rain
- Stavanger in SeptemberNorway · 302 kmHigh 14.4°C · Low 10.7°C · 201 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Oslo) is explained once on the Oslo year overview and on the Sources, method and limits page.