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