ERA5 almanac — 8 years of real data

Seattle in July

Seattle in July: 10% of days see measurable rain, 78°F average high, 70% of days historically clear (n=248, ERA5 2018–2025).

Historically one of the better months to visit Seattle for sun: 70% of days are clear on average (n=248, avg high 78°F). Every percentage here is a historical average from 8 years of ERA5 data — 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 Seattle 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 Seattle 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	62%	n=120	78°F
Late July 16th–end	77%	n=128	78°F
Full month average	70%	n=248	78°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 Seattle 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	74%	n=120
Late July 16th–end	89%	n=128
Full month average	82%	n=248

14.7 h median sunshine per day 88% of days exceed 8 h sunshine 10% of days see ≥ 1 mm rain — rain is not hidden

Comparison (old vs new): WMO-code “clear” bar: 70%. Sunshine-based “warm & sunny”: 82%. The 12-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

Seattle clears solidly in July: 70% of days historically (n=248), avg high 78°F. Most trips here in July will find more sun than cloud.

Every month in Seattle

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

Historical clear-sky % for Seattle, 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	1%	n=240	All destinations →
May	13%	n=248	All destinations →
June	32%	n=240	All destinations →
July ← this page	70%	n=248	All destinations →
August	61%	n=248	All destinations →
September	30%	n=240	All destinations →
October	3%	n=248	All destinations →
November	0%	n=240	All destinations →
December	0%	n=248	All destinations →

Frequently asked

Does it rain in Seattle in July?

Rarely. Only 10% of days in Seattle see measurable rain in July, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

Is Seattle good for sun in July?

Yes. Seattle is historically strong for sun in July: 70% of days are clear on average (avg high 78°F, n=248 days, ERA5 2018–2025).

How Seattle compares in July

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

→ Seattle vs Sun Valley in July — Sun Valley is 70% clear historically
→ Seattle vs Newport Beach in July — Newport Beach is 71% clear historically
→ Seattle vs Whitefish in July — Whitefish is 71% clear historically

→ Seattle 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.