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SunnyDays

ERA5 almanac — 8 years of real data

Aspen in July

Aspen in July is a mixed month for sun: 43% of days historically clear (n=248, avg high 80°F). The outcome varies year to year — check the early/late split below. 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 Aspen 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 July

Clear-sky percentage for Aspen in July, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early July
1st–15th		 43% n=120 80°F
Late July
16th–end		 43% n=128 80°F
Full month average 43% n=248 80°F

Sunshine & warmth in July

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 Aspen in July. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early July
1st–15th		 97% n=120
Late July
16th–end		 98% n=128
Full month average 98% n=248
14.0 h median sunshine per day 98% of days exceed 8 h sunshine 22% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 43%. Sunshine-based “warm & sunny”: 98%. 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

Aspen in July is genuinely mixed: 43% of days historically clear (n=248), avg high 80°F — more cloudy than clear. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Aspen

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

Historical clear-sky % for Aspen, 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 0% n=240 All destinations →
May 3% n=248 All destinations →
June 34% n=240 All destinations →
July ← this page 43% n=248 All destinations →
August 47% n=248 All destinations →
September 39% n=240 All destinations →
October 2% n=248 All destinations →
November 0% n=240 All destinations →
December 0% n=248 All destinations →

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.