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.
30 days — Oslo
14 real + 16 synthesised
Sat · Today Cloudy
+16°+7°2,1 mm
Sun · Tomorrow Cloudy
+18°+8°12%
Monday 7/9 Showers
+18°+10°2,1 mm
Tuesday 8/9 Partly cloudy
+19°+10°0,2 mm
Wednesday 9/9 Showers
+15°+6°0,7 mm
Thursday 10/9 Fog
+11°+8°1,8 mm
Friday 11/9 Fog
+13°+8°2,4 mm
Saturday 12/9 Cloudy
+15°+8°12%
Sunday 13/9 Clear
+18°+7°7%
Monday 14/9 Cloudy
+14°+6°16%
Tuesday 15/9 Cloudy
+15°+5°20%
Wednesday 16/9 Cloudy
+14°+8°1,2 mm
Thursday 17/9 Showers
+11°+6°8,6 mm
Friday 18/9 Clear
+14°+4°7%
Saturday 19/9 Rain (climate normal)
+14°+6°5,7 mm
Sunday 20/9 Partly cloudy (climate normal)
+17°+8°20%
Monday 21/9 Partly cloudy (climate normal)
+19°+9°20%
Tuesday 22/9 Rain (climate normal)
+17°+8°10,2 mm
Wednesday 23/9 Partly cloudy (climate normal)
+15°+7°20%
Thursday 24/9 Partly cloudy (climate normal)
+14°+6°20%
Friday 25/9 Rain (climate normal)
+13°+6°11,1 mm
Saturday 26/9 Partly cloudy (climate normal)
+16°+8°20%
Sunday 27/9 Partly cloudy (climate normal)
+18°+9°20%
Monday 28/9 Rain (climate normal)
+19°+9°7,2 mm
Tuesday 29/9 Partly cloudy (climate normal)
+17°+8°20%
Wednesday 30/9 Partly cloudy (climate normal)
+15°+7°20%
Thursday 1/10 Rain (climate normal)
+7°+2°10,4 mm
Friday 2/10 Partly cloudy (climate normal)
+8°+2°20%
Saturday 3/10 Partly cloudy (climate normal)
+10°+3°20%
Sunday 4/10 Rain (climate normal)
+10°+3°7,8 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.