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SunnyDays

ERA5 almanac — 8 years of real data

Lisbon in August

Lisbon in August: 2% of days see measurable rain, 84°F average high, 91% of days historically clear (n=248, ERA5 2018–2025).

Historically one of the better months to visit Lisbon for sun: 91% of days are clear on average (n=248, avg high 84°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 Lisbon 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 Lisbon 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		 93% n=120 84°F
Late August
16th–end		 90% n=128 84°F
Full month average 91% n=248 84°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 Lisbon 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		 99% n=120
Late August
16th–end		 99% n=128
Full month average 99% n=248
12.9 h median sunshine per day 99% of days exceed 8 h sunshine 2% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 91%. Sunshine-based “warm & sunny”: 99%.

Bottom line

Lisbon is historically one of the best destinations for sun in August: 91% of days meet the clear bar (avg high 84°F, n=248 days across 8 years). Pack for outdoor activity — this month consistently delivers.

Every month in Lisbon

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

Historical clear-sky % for Lisbon, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 7% n=248 All destinations →
April 19% n=240 All destinations →
May 49% n=248 All destinations →
June 58% n=240 All destinations →
July 85% n=248 All destinations →
August ← this page 91% n=248 All destinations →
September 66% n=240 All destinations →
October 42% n=248 All destinations →
November 2% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Lisbon in August?

Rarely. Only 2% of days in Lisbon see measurable rain in August, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

Is Lisbon good for sun in August?

Yes. Lisbon is historically strong for sun in August: 91% of days are clear on average (avg high 84°F, n=248 days, ERA5 2018–2025).

How Lisbon compares in August

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Lisbon 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.