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 Harstad 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 — Harstad
14 real + 16 synthesised
Sat · Today Cloudy
+12°+8°0,6 mm
Sun · Tomorrow Showers
+11°+8°5,9 mm
Monday 5/10 Light rain
+9°+7°44,5 mm
Tuesday 6/10 Drizzle
+8°+5°9,9 mm
Wednesday 7/10 Showers
+5°+4°4,1 mm
Thursday 8/10 Showers
+4°+2°4,5 mm
Friday 9/10 Cloudy
+3°+1°15%
Saturday 10/10 Cloudy
+5°+2°22%
Sunday 11/10 Cloudy
+4°+2°14%
Monday 12/10 Cloudy
+5°+3°0,6 mm
Tuesday 13/10 Clear
+4°+2°3,9 mm
Wednesday 14/10 Clear
+4°+2°10%
Thursday 15/10 Clear
+2°+1°9%
Friday 16/10 Cloudy
+3°+1°23%
Saturday 17/10 Rain (climate normal)
+1°-5°5,9 mm
Sunday 18/10 Partly cloudy (climate normal)
+3°-4°20%
Monday 19/10 Partly cloudy (climate normal)
+1°-5°20%
Tuesday 20/10 Rain (climate normal)
+3°-5°8,1 mm
Wednesday 21/10 Partly cloudy (climate normal)
-2°-7°20%
Thursday 22/10 Partly cloudy (climate normal)
-3°-8°20%
Friday 23/10 Rain (climate normal)
-3°-8°11,2 mm
Saturday 24/10 Partly cloudy (climate normal)
-1°-7°20%
Sunday 25/10 Partly cloudy (climate normal)
+1°-5°20%
Monday 26/10 Rain (climate normal)
+2°-5°5,3 mm
Tuesday 27/10 Partly cloudy (climate normal)
0°-6°20%
Wednesday 28/10 Partly cloudy (climate normal)
0°-6°20%
Thursday 29/10 Rain (climate normal)
-3°-8°9,8 mm
Friday 30/10 Partly cloudy (climate normal)
-2°-7°20%
Saturday 31/10 Partly cloudy (climate normal)
+1°-5°20%
Sunday 1/11 Rain (climate normal)
-3°-8°7,8 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.