Days 1-14 are a real forecast from global weather models. Days 15-30 are season-typical values based on climate normals 1991-2020 (MET) — good for planning, NOT an exact forecast that far ahead.
The forecast for Oslo and the places around it comes from the same weather models as the place pages. Radar: RainViewer, images from the last two hours.
30 days — Oslo
14 real + 16 synthesised
Tue · Today Clear
+8°0°19%
Wed · Tomorrow Cloudy
+7°+5°6,2 mm
Thursday 22/10 Fog
+10°+6°14,9 mm
Friday 23/10 Fog
+9°+4°1,0 mm
Saturday 24/10 Drizzle
+8°+3°7,5 mm
Sunday 25/10 Fog
+8°+4°18,2 mm
Monday 26/10 Showers
+9°+6°3,5 mm
Tuesday 27/10 Fog
+9°+7°0,2 mm
Wednesday 28/10 Light rain
+11°+8°18,7 mm
Thursday 29/10 Fog
+9°+3°2,7 mm
Friday 30/10 Cloudy
+7°+3°2,4 mm
Saturday 31/10 Showers
+6°+1°1,3 mm
Sunday 1/11 Clear
+8°0°16%
Monday 2/11 Partly cloudy
+6°-1°14%
Tuesday 3/11 Rain (climate normal)
+2°-2°4,6 mm
Wednesday 4/11 Partly cloudy (climate normal)
+5°0°20%
Thursday 5/11 Partly cloudy (climate normal)
+7°+1°20%
Friday 6/11 Rain (climate normal)
+5°0°8,3 mm
Saturday 7/11 Partly cloudy (climate normal)
+3°-1°20%
Sunday 8/11 Partly cloudy (climate normal)
+2°-2°20%
Monday 9/11 Rain (climate normal)
+1°-2°9,0 mm
Tuesday 10/11 Partly cloudy (climate normal)
+4°0°20%
Wednesday 11/11 Partly cloudy (climate normal)
+6°+1°20%
Thursday 12/11 Rain (climate normal)
+7°+1°5,8 mm
Friday 13/11 Partly cloudy (climate normal)
+5°0°20%
Saturday 14/11 Partly cloudy (climate normal)
+3°-1°20%
Sunday 15/11 Rain (climate normal)
+1°-2°9,0 mm
Monday 16/11 Partly cloudy (climate normal)
+2°-2°20%
Tuesday 17/11 Partly cloudy (climate normal)
+4°-1°20%
Wednesday 18/11 Rain (climate normal)
+4°-1°6,8 mm
How does the long-range forecast work?
Days 1-14: Fetched live from global weather models (ECMWF, GFS) with statistical correction. Reliability about 85 % for days 1-3, about 60 % for days 7-10, about 45 % for days 11-14.
Days 15-30: A real forecast does not exist that far ahead (chaotic system). Instead we show season-typical values: the monthly average Tmax/Tmin from climate normals 1991-2020, with mild weekly variation.
Use: «About how warm is it usually in Oslo the last week of July?» — a good question for days 15-30. «Will it rain on 27 May?» — no serious forecast can answer that.