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SunnyDays

ERA5 almanac — 8 years of real data

Algarve in May

Algarve in May: 10% of days see measurable rain, 75°F average high, 57% of days historically clear (n=248, ERA5 2018–2025).

Algarve in May is a mixed month for sun: 57% of days historically clear (n=248, avg high 75°F). The outcome varies year to year — check the early/late split below. 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 Algarve 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 May

Clear-sky percentage for Algarve in May, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early May
1st–15th		 46% n=120 75°F
Late May
16th–end		 68% n=128 75°F
Full month average 57% n=248 75°F

Sunshine & warmth in May

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 Algarve in May. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early May
1st–15th		 48% n=120
Late May
16th–end		 71% n=128
Full month average 60% n=248
13.1 h median sunshine per day 98% 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: 57%. Sunshine-based “warm & sunny”: 60%.

Bottom line

Algarve in May is genuinely mixed: 57% of days historically clear (n=248), avg high 75°F — more clear than cloudy. The two halves differ materially (46% early, 68% late) — favour the late half of the month. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Algarve

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

Historical clear-sky % for Algarve, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 1% n=226 All destinations →
March 5% n=248 All destinations →
April 20% n=240 All destinations →
May ← this page 57% n=248 All destinations →
June 76% n=240 All destinations →
July 98% n=248 All destinations →
August 98% n=248 All destinations →
September 80% n=240 All destinations →
October 53% n=248 All destinations →
November 4% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Algarve in May?

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

Is Algarve good for sun in May?

It's mixed. Algarve in May is clear on 57% of days historically (avg high 75°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Algarve compares in May

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