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SunnyDays

ERA5 almanac — 8 years of real data

Burlington in September

Burlington in September: 34% of days see measurable rain, 72°F average high, 26% of days historically clear (n=240, ERA5 2018–2025).

Burlington in September is historically a poor month for sun: only 26% of days clear across 8 years (n=240, avg high 72°F). July is the clearest month for Burlington 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 Burlington 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 Burlington 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		 32% n=120 72°F
Late September
16th–end		 21% n=120 72°F
Full month average 26% n=240 72°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 Burlington 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		 59% n=120
Late September
16th–end		 29% n=120
Full month average 44% n=240
11.5 h median sunshine per day 76% 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: 26%. Sunshine-based “warm & sunny”: 44%. 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

Burlington is mostly overcast in September historically: only 26% of days are clear across 8 years (n=240), avg high 72°F. If you want sun in Burlington, July is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in July — historically the best month for sun in Burlington.

Every month in Burlington

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

Historical clear-sky % for Burlington, 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 15% n=248 All destinations →
June 27% n=240 All destinations →
July 32% n=248 All destinations →
August 31% n=248 All destinations →
September ← this page 26% 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 Burlington in September?

Sometimes. Burlington 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 Burlington good for sun in September?

Not usually. Burlington is historically overcast in September: only 26% of days are clear (avg high 72°F, n=240 days, ERA5 2018–2025). July is historically far better for sun here.

How Burlington compares in September

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