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SunnyDays

ERA5 almanac — 8 years of real data

Athens in May

Athens in May: 16% of days see measurable rain, 77°F average high, 57% of days historically clear (n=248, ERA5 2018–2025).

Athens in May is a mixed month for sun: 57% of days historically clear (n=248, avg high 77°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 Athens 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 Athens 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		 50% n=120 77°F
Late May
16th–end		 64% n=128 77°F
Full month average 57% n=248 77°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 Athens 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		 65% n=120
Late May
16th–end		 89% n=128
Full month average 77% n=248
13.0 h median sunshine per day 94% of days exceed 8 h sunshine 16% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 57%. Sunshine-based “warm & sunny”: 77%. 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

Athens in May is genuinely mixed: 57% of days historically clear (n=248), avg high 77°F — more clear than cloudy. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Athens

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

Historical clear-sky % for Athens, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 4% n=248 All destinations →
April 24% n=240 All destinations →
May ← this page 57% n=248 All destinations →
June 69% n=240 All destinations →
July 82% n=248 All destinations →
August 79% n=248 All destinations →
September 72% n=240 All destinations →
October 56% n=248 All destinations →
November 7% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Athens in May?

Rarely. Only 16% of days in Athens 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 Athens good for sun in May?

It's mixed. Athens in May is clear on 57% of days historically (avg high 77°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Athens compares in May

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