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SunnyDays

ERA5 almanac — 8 years of real data

Las Vegas in August

Historically one of the better months to visit Las Vegas for sun: 85% of days are clear on average (n=248, avg high 104°F). Every percentage here is a historical average from 8 years of ERA5 data — 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 Las Vegas 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 August

Clear-sky percentage for Las Vegas in August, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early August
1st–15th		 82% n=120 104°F
Late August
16th–end		 87% n=128 104°F
Full month average 85% n=248 104°F

Sunshine & warmth in August

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 Las Vegas in August. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early August
1st–15th		 98% n=120
Late August
16th–end		 98% n=128
Full month average 98% n=248
12.9 h median sunshine per day 97% of days exceed 8 h sunshine 5% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 85%. Sunshine-based “warm & sunny”: 98%. The 13-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

Las Vegas is historically one of the best US destinations for sun in August: 85% of days meet the clear bar (avg high 104°F, n=248 days across 8 years). Pack for outdoor activity — this month consistently delivers.

Every month in Las Vegas

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

Historical clear-sky % for Las Vegas, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 15% n=226 All destinations →
March 32% n=248 All destinations →
April 84% n=240 All destinations →
May 88% n=248 All destinations →
June 95% n=240 All destinations →
July 88% n=248 All destinations →
August ← this page 85% n=248 All destinations →
September 92% n=240 All destinations →
October 82% n=248 All destinations →
November 34% 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.