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SunnyDays

ERA5 almanac — 8 years of real data

Kyoto in September

Kyoto in September: 50% of days see measurable rain, 84°F average high, 25% of days historically clear (n=240, ERA5 2018–2025).

Kyoto in September is historically a poor month for sun: only 25% of days clear across 8 years (n=240, avg high 84°F). May is the clearest month for Kyoto historically. 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 Kyoto 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 Kyoto 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		 18% n=120 84°F
Late September
16th–end		 32% n=120 84°F
Full month average 25% 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 Kyoto 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		 81% n=120
Late September
16th–end		 78% n=120
Full month average 80% n=240
9.8 h median sunshine per day 66% of days exceed 8 h sunshine 50% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 25%. Sunshine-based “warm & sunny”: 80%. The 55-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

Kyoto is mostly overcast in September historically: only 25% of days are clear across 8 years (n=240), avg high 84°F. If you want sun in Kyoto, May is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in May — historically the best month for sun in Kyoto.

Every month in Kyoto

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

Historical clear-sky % for Kyoto, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 1% n=248 All destinations →
April 12% n=240 All destinations →
May 32% n=248 All destinations →
June 31% n=240 All destinations →
July 21% n=248 All destinations →
August 26% n=248 All destinations →
September ← this page 25% n=240 All destinations →
October 22% n=248 All destinations →
November 2% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Kyoto in September?

Yes, frequently. In Kyoto, 50% of days in September see measurable rain, based on 8 years of ERA5 historical data (n=240 days, 2018–2025). This is a historical average, not a forecast.

Is Kyoto good for sun in September?

Not usually. Kyoto is historically overcast in September: only 25% of days are clear (avg high 84°F, n=240 days, ERA5 2018–2025). May is historically far better for sun here.

How Kyoto compares in September

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