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