Skip to main content
SunnyDays

ERA5 almanac — 8 years of real data

Phoenix in March

Phoenix in March is a mixed month for sun: 61% of days historically clear (n=248, avg high 76°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 Phoenix 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 March

Clear-sky percentage for Phoenix in March, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early March
1st–15th		 54% n=120 76°F
Late March
16th–end		 67% n=128 76°F
Full month average 61% n=248 76°F

Sunshine & warmth in March

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 Phoenix in March. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early March
1st–15th		 63% n=120
Late March
16th–end		 74% n=128
Full month average 69% n=248
11.2 h median sunshine per day 92% of days exceed 8 h sunshine 13% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 61%. Sunshine-based “warm & sunny”: 69%.

Bottom line

Phoenix clears solidly in March: 61% of days historically (n=248), avg high 76°F. Most trips here in March will find more sun than cloud.

Every month in Phoenix

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

Historical clear-sky % for Phoenix, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 17% n=248 All destinations →
February 41% n=226 All destinations →
March ← this page 61% n=248 All destinations →
April 94% n=240 All destinations →
May 95% n=248 All destinations →
June 94% n=240 All destinations →
July 76% n=248 All destinations →
August 76% n=248 All destinations →
September 82% n=240 All destinations →
October 85% n=248 All destinations →
November 63% n=240 All destinations →
December 22% 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.