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SunnyDays

ERA5 almanac — 8 years of real data

Athens in September

Athens in September: 10% of days see measurable rain, 84°F average high, 72% of days historically clear (n=240, ERA5 2018–2025).

Historically one of the better months to visit Athens for sun: 72% of days are clear on average (n=240, 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 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 September

Clear-sky percentage for Athens in September, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early September
1st–15th		 72% n=120 84°F
Late September
16th–end		 72% n=120 84°F
Full month average 72% n=240 84°F

Sunshine & warmth in September

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 September. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early September
1st–15th		 98% n=120
Late September
16th–end		 91% n=120
Full month average 94% n=240
11.8 h median sunshine per day 96% 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: 72%. Sunshine-based “warm & sunny”: 94%. 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

Athens clears solidly in September: 72% of days historically (n=240), avg high 84°F. Most trips here in September will find more sun than cloud.

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 57% n=248 All destinations →
June 69% n=240 All destinations →
July 82% n=248 All destinations →
August 79% n=248 All destinations →
September ← this page 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 September?

Rarely. Only 10% of days in Athens see measurable rain in September, based on 8 years of ERA5 historical data (n=240 days, 2018–2025). This is a historical average, not a forecast.

Is Athens good for sun in September?

Yes. Athens is historically strong for sun in September: 72% of days are clear on average (avg high 84°F, n=240 days, ERA5 2018–2025).

How Athens compares in September

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.