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SunnyDays

ERA5 almanac — 8 years of real data

London in August

London in August: 27% of days see measurable rain, 73°F average high, 28% of days historically clear (n=248, ERA5 2018–2025).

London in August is historically a poor month for sun: only 28% of days clear across 8 years (n=248, avg high 73°F). July is the clearest month for London historically. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live London page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late August

Clear-sky percentage for London in August, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early August
1st–15th		 38% n=120 73°F
Late August
16th–end		 19% n=128 73°F
Full month average 28% n=248 73°F

Sunshine & warmth in August

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for London in August. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early August
1st–15th		 58% n=120
Late August
16th–end		 38% n=128
Full month average 48% n=248
11.2 h median sunshine per day 73% of days exceed 8 h sunshine 27% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 28%. Sunshine-based “warm & sunny”: 48%. The 20-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

Bottom line

London is mostly overcast in August historically: only 28% of days are clear across 8 years (n=248), avg high 73°F. If you want sun in London, July is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in July — historically the best month for sun in London.

Every month in London

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for London, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 0% n=248 All destinations →
April 5% n=240 All destinations →
May 8% n=248 All destinations →
June 24% n=240 All destinations →
July 28% n=248 All destinations →
August ← this page 28% n=248 All destinations →
September 14% n=240 All destinations →
October 2% n=248 All destinations →
November 0% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in London in August?

Sometimes. London sees measurable rain on 27% of days in August historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is London good for sun in August?

Not usually. London is historically overcast in August: only 28% of days are clear (avg high 73°F, n=248 days, ERA5 2018–2025). July is historically far better for sun here.

How London compares in August

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against London this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.