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