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SunnyDays

ERA5 almanac — 8 years of real data

Stowe in September

Stowe in September: 34% of days see measurable rain, 70°F average high, 18% of days historically clear (n=240, ERA5 2018–2025).

Stowe in September is historically a poor month for sun: only 18% of days clear across 8 years (n=240, avg high 70°F). August is the clearest month for Stowe 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 Stowe 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 Stowe 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		 22% n=120 70°F
Late September
16th–end		 14% n=120 70°F
Full month average 18% n=240 70°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 Stowe 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		 49% n=120
Late September
16th–end		 23% n=120
Full month average 36% n=240
10.7 h median sunshine per day 72% of days exceed 8 h sunshine 34% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 18%. Sunshine-based “warm & sunny”: 36%. The 18-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

Stowe is a poor choice for sun in September: just 18% of days clear historically (n=240). August is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in August — historically the best month for sun in Stowe.

Every month in Stowe

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

Historical clear-sky % for Stowe, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 0% n=248 All destinations →
April 2% n=240 All destinations →
May 14% n=248 All destinations →
June 21% n=240 All destinations →
July 24% n=248 All destinations →
August 25% n=248 All destinations →
September ← this page 18% n=240 All destinations →
October 6% n=248 All destinations →
November 0% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Stowe in September?

Sometimes. Stowe sees measurable rain on 34% of days in September historically (n=240 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Stowe good for sun in September?

Not usually. Stowe is historically overcast in September: only 18% of days are clear (avg high 70°F, n=240 days, ERA5 2018–2025). August is historically far better for sun here.

How Stowe compares in September

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