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
Mon · Today Showers
+14°+9°5,4 mm
Tue · Tomorrow Showers
+14°+10°0,4 mm
Wednesday 5/8 Partly cloudy
+14°+9°7,0 mm
Thursday 6/8 Showers
+16°+9°1,2 mm
Friday 7/8 Showers
+14°+9°1,0 mm
Saturday 8/8 Clear
+14°+7°10%
Sunday 9/8 Partly cloudy
+12°+7°12%
Monday 10/8 Clear
+13°+8°8%
Tuesday 11/8 Clear
+14°+8°8%
Wednesday 12/8 Partly cloudy
+13°+8°22%
Thursday 13/8 Cloudy
+12°+10°3,5 mm
Friday 14/8 Partly cloudy
+17°+11°2,7 mm
Saturday 15/8 Partly cloudy
+17°+12°18%
Sunday 16/8 Clear
+16°+10°8%
Monday 17/8 Rain (climate normal)
+17°+10°9,9 mm
Tuesday 18/8 Partly cloudy (climate normal)
+19°+12°20%
Wednesday 19/8 Partly cloudy (climate normal)
+20°+12°20%
Thursday 20/8 Rain (climate normal)
+18°+11°6,7 mm
Friday 21/8 Partly cloudy (climate normal)
+18°+11°20%
Saturday 22/8 Partly cloudy (climate normal)
+16°+10°20%
Sunday 23/8 Rain (climate normal)
+17°+10°5,2 mm
Monday 24/8 Partly cloudy (climate normal)
+20°+12°20%
Tuesday 25/8 Partly cloudy (climate normal)
+22°+13°20%
Wednesday 26/8 Rain (climate normal)
+21°+13°9,9 mm
Thursday 27/8 Partly cloudy (climate normal)
+21°+13°20%
Friday 28/8 Partly cloudy (climate normal)
+17°+10°20%
Saturday 29/8 Rain (climate normal)
+16°+10°10,4 mm
Sunday 30/8 Partly cloudy (climate normal)
+17°+10°20%
Monday 31/8 Partly cloudy (climate normal)
+18°+11°20%
Tuesday 1/9 Rain (climate normal)
+14°+8°9,8 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.