ERA5 almanac — 8 years of real data

London in July

London in July: 31% of days see measurable rain, 74°F average high, 28% of days historically clear (n=248, ERA5 2018–2025).

London in July is historically a poor month for sun: only 28% of days clear across 8 years (n=248, avg high 74°F). 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 July

Clear-sky percentage for London in July, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period	% Clear days	Sample (n)	Avg high
Early July 1st–15th	23%	n=120	74°F
Late July 16th–end	33%	n=128	74°F
Full month average	28%	n=248	74°F

Sunshine & warmth in July

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 July. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period	Warm & sunny (≥72°F, >6 h sun)	Sample (n)
Early July 1st–15th	40%	n=120
Late July 16th–end	59%	n=128
Full month average	50%	n=248

12.9 h median sunshine per day 80% of days exceed 8 h sunshine 31% of days see ≥ 1 mm rain — rain is not hidden

Comparison (old vs new): WMO-code “clear” bar: 28%. Sunshine-based “warm & sunny”: 50%. The 22-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 July historically: only 28% of days are clear across 8 years (n=248), avg high 74°F. Most visitors this month will see more clouds than sun.

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 ← this page	28%	n=248	All destinations →
August	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 July?

Sometimes. London sees measurable rain on 31% of days in July historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is London good for sun in July?

Not usually. London is historically overcast in July: only 28% of days are clear (avg high 74°F, n=248 days, ERA5 2018–2025).

How London compares in July

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.

→ London vs Amsterdam in July — Amsterdam is 19% clear historically
→ London vs Paris in July — Paris is 45% clear historically
→ London vs Venice in July — Venice is 52% clear historically

→ London live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in July — all destinations ranked by July clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

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.