Days 1-14 are a real forecast from global weather models. Days 15-30 are season-typical values based on SMHI climate normals 1991-2020 — good for planning, NOT an exact forecast that far ahead.
30 days — Piteå
14 real + 16 synthesised
Fri · Today Showers
+20°+12°6,8 mm
Sat · Tomorrow Clear
+20°+9°0,6 mm
Sunday 2/8 Partly cloudy
+20°+10°0,3 mm
Monday 3/8 Partly cloudy
+18°+10°13%
Tuesday 4/8 Clear
+19°+8°6%
Wednesday 5/8 Showers
+15°+7°1,0 mm
Thursday 6/8 Partly cloudy
+16°+8°0,3 mm
Friday 7/8 Partly cloudy
+14°+8°2,2 mm
Saturday 8/8 Showers
+16°+9°0,3 mm
Sunday 9/8 Cloudy
+16°+8°0,6 mm
Monday 10/8 Showers
+15°+8°1,8 mm
Tuesday 11/8 Partly cloudy
+16°+8°14%
Wednesday 12/8 Partly cloudy
+16°+9°1,5 mm
Thursday 13/8 Partly cloudy
+18°+11°3,9 mm
Friday 14/8 Rain (climate normal)
+17°+7°3,7 mm
Saturday 15/8 Partly cloudy (climate normal)
+19°+8°20%
Sunday 16/8 Partly cloudy (climate normal)
+18°+7°20%
Monday 17/8 Rain (climate normal)
+18°+7°6,2 mm
Tuesday 18/8 Partly cloudy (climate normal)
+15°+6°20%
Wednesday 19/8 Partly cloudy (climate normal)
+14°+5°20%
Thursday 20/8 Rain (climate normal)
+13°+4°4,2 mm
Friday 21/8 Partly cloudy (climate normal)
+17°+7°20%
Saturday 22/8 Partly cloudy (climate normal)
+17°+7°20%
Sunday 23/8 Rain (climate normal)
+17°+7°3,5 mm
Monday 24/8 Partly cloudy (climate normal)
+16°+6°20%
Tuesday 25/8 Partly cloudy (climate normal)
+14°+5°20%
Wednesday 26/8 Rain (climate normal)
+15°+5°8,6 mm
Thursday 27/8 Partly cloudy (climate normal)
+13°+4°20%
Friday 28/8 Partly cloudy (climate normal)
+15°+5°20%
Saturday 29/8 Rain (climate normal)
+17°+7°7,9 mm
How does the long-range forecast work?
Days 1-14: Fetched live from global weather models (ECMWF, GFS) with statistical correction. Reliability ~85% for days 1-3, ~60% for days 7-10, ~45% for days 11-14.
Days 15-30: A real forecast does not exist that far ahead (a chaotic system). Instead we show season-typical values: the month’s average Tmax/Tmin from SMHI climate normals 1991-2020 (Stockholm baseline with latitude correction for Piteå), with mild weekly variation.
Use: "Roughly how warm is it usually in Stockholm in the last week of July?" — a good question for days 15-30. "Will it rain on 27 May?" — no serious forecast can say.