Days 1-14 are a real forecast from weather models. Days 15-30 are season-typical values based on 1991-2020 climate averages — good for planning, NOT an exact forecast that far ahead.
30 days — Cardiff
14 real + 16 synthesised
Wed · Today Sunny
25°15°9%
Thu · Tomorrow Sunny
22°13°7%
Friday 31/7 Sunny
22°10°3%
Saturday 1/8 Sunny
22°10°3%
Sunday 2/8 Sunny intervals
21°11°6%
Monday 3/8 Sunny intervals
23°16°0.4 mm
Tuesday 4/8 Showers
21°13°0.6 mm
Wednesday 5/8 Sunny
21°10°5%
Thursday 6/8 Sunny
23°12°3%
Friday 7/8 Sunny
24°11°3%
Saturday 8/8 Sunny
24°12°3%
Sunday 9/8 Sunny
24°12°3%
Monday 10/8 Sunny
26°14°2%
Tuesday 11/8 Sunny
26°14°1%
Wednesday 12/8 Rain (climate average)
29°19°4.4 mm
Thursday 13/8 Sunny intervals (climate average)
30°20°20%
Friday 14/8 Sunny intervals (climate average)
34°22°20%
Saturday 15/8 Rain (climate average)
32°21°5.3 mm
Sunday 16/8 Sunny intervals (climate average)
29°19°20%
Monday 17/8 Sunny intervals (climate average)
28°19°20%
Tuesday 18/8 Rain (climate average)
28°19°7.9 mm
Wednesday 19/8 Sunny intervals (climate average)
28°19°20%
Thursday 20/8 Sunny intervals (climate average)
31°21°20%
Friday 21/8 Rain (climate average)
33°22°3.7 mm
Saturday 22/8 Sunny intervals (climate average)
30°20°20%
Sunday 23/8 Sunny intervals (climate average)
28°19°20%
Monday 24/8 Rain (climate average)
28°18°4.2 mm
Tuesday 25/8 Sunny intervals (climate average)
29°19°20%
Wednesday 26/8 Sunny intervals (climate average)
30°20°20%
Thursday 27/8 Rain (climate average)
32°21°6.8 mm
How does the long-range forecast work?
Days 1-14: Fetched live from weather models (UKV, 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 max/min from 1991-2020 climate data (London baseline with latitude correction for Cardiff), with mild weekly variation.
Use: "Roughly how warm is it usually in London in the last week of July?" — a good question for days 15-30. "Will it rain on 27 May?" — no serious forecast can say.
Forecasts from the UK Met Office UKV model, global weather models and official UK environmental data · Met Office UKV model · Environment Agency · Copernicus CAMS · NOAA