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SunnyDays

ERA5 almanac — 8 years of real data

Shenandoah Valley in September

Shenandoah Valley in September: rain frequency data not yet backfilled for this month, 78°F average high, 36% of days historically clear (n=240, ERA5 2018–2025).

Shenandoah Valley in September is historically a poor month for sun: only 36% of days clear across 8 years (n=240, avg high 78°F). 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 Shenandoah Valley 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 Shenandoah Valley 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		 49% n=120 78°F
Late September
16th–end		 24% n=120 78°F
Full month average 36% n=240 78°F

Bottom line

Shenandoah Valley is mostly overcast in September historically: only 36% of days are clear across 8 years (n=240), avg high 78°F. The two halves differ materially (49% early, 24% late) — favour the early half of the month. Most visitors this month will see more clouds than sun.

Every month in Shenandoah Valley

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

Historical clear-sky % for Shenandoah Valley, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 1% n=226 All destinations →
March 2% n=248 All destinations →
April 14% n=240 All destinations →
May 18% n=248 All destinations →
June 39% n=240 All destinations →
July 34% n=248 All destinations →
August 34% n=248 All destinations →
September ← this page 36% n=240 All destinations →
October 17% n=248 All destinations →
November 4% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Is Shenandoah Valley good for sun in September?

It's mixed. Shenandoah Valley in September is clear on 36% of days historically (avg high 78°F, n=240 days, ERA5 2018–2025) — the outcome varies year to year.

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.