ERA5 almanac comparison — 8 years of real data
Phoenix vs San Diego: weather in March
Phoenix is the clear winner for sun in March: 61% of days historically clear versus just 6% in San Diego — a 55-point gap across 8 years of ERA5 data. San Diego also sees measurably more rain than Phoenix this month (33% vs 13% of days). This isn't close.
What you are reading: 8-year historical averages, not a forecast.
Either destination can still surprise you this specific March. For this
week’s actual forecast, each destination links to its live page below.
Phoenix
AZ
- Clear days, March
- 61%
- Sample size
- n=248 days
- Avg high
- 76°F
- Early March (1st–15th)
- 54%
- Late March (16th–end)
- 67%
- Rain frequency
- 13% of days
San Diego
CA
- Clear days, March
- 6%
- Sample size
- n=248 days
- Avg high
- 64°F
- Early March (1st–15th)
- 3%
- Late March (16th–end)
- 9%
- Rain frequency
- 33% of days
Compare Phoenix vs San Diego in another month
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.