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 Trondheim 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 — Trondheim
14 real + 16 synthesised
Tue · Today Clear
+9°+6°5%
Wed · Tomorrow Clear
+11°+6°9%
Thursday 22/10 Cloudy
+12°+9°19%
Friday 23/10 Cloudy
+12°+9°0,6 mm
Saturday 24/10 Cloudy
+11°+7°23%
Sunday 25/10 Cloudy
+11°+9°8%
Monday 26/10 Cloudy
+11°+9°9%
Tuesday 27/10 Clear
+11°+7°9%
Wednesday 28/10 Cloudy
+13°+10°14%
Thursday 29/10 Cloudy
+12°+8°0,8 mm
Friday 30/10 Light rain
+7°+5°15,6 mm
Saturday 31/10 Showers
+8°+6°1,4 mm
Sunday 1/11 Showers
+8°+6°5,9 mm
Monday 2/11 Showers
+8°+7°3,2 mm
Tuesday 3/11 Rain (climate normal)
+2°-2°8,7 mm
Wednesday 4/11 Partly cloudy (climate normal)
+4°0°20%
Thursday 5/11 Partly cloudy (climate normal)
+5°0°20%
Friday 6/11 Rain (climate normal)
+3°-1°5,9 mm
Saturday 7/11 Partly cloudy (climate normal)
+3°-1°20%
Sunday 8/11 Partly cloudy (climate normal)
+1°-2°20%
Monday 9/11 Rain (climate normal)
+2°-2°4,6 mm
Tuesday 10/11 Partly cloudy (climate normal)
+5°0°20%
Wednesday 11/11 Partly cloudy (climate normal)
+7°+1°20%
Thursday 12/11 Rain (climate normal)
+6°+1°8,7 mm
Friday 13/11 Partly cloudy (climate normal)
+6°+1°20%
Saturday 14/11 Partly cloudy (climate normal)
+2°-2°20%
Sunday 15/11 Rain (climate normal)
+1°-2°9,2 mm
Monday 16/11 Partly cloudy (climate normal)
+2°-2°20%
Tuesday 17/11 Partly cloudy (climate normal)
+3°-1°20%
Wednesday 18/11 Rain (climate normal)
+4°0°6,7 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.