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Phoenix vs San Diego weather: climate comparison
Phoenix is the warmer of the two, averaging 73°F (23°C) over the year against 63°F (17°C) in San Diego. San Diego is wetter, with 11.7 in (298 mm) of precipitation a year to Phoenix's 9.6 in (243 mm). Below: every month side by side, from 30 years of ERA5 data (1996–2025).
- Mean temperature
- 23.0°C Phoenix
17.0°C San Diego - Annual precipitation
- 243.4 mm Phoenix
298.4 mm San Diego - Rainy days a year
- 30 Phoenix
38 San Diego - Sunshine per day
- 11.1 h Phoenix
10.9 h San Diego
Month by month
| Month | Phoenix | San Diego |
|---|---|---|
| January | 18.9°C | 17.5°C |
| February | 20.8°C | 17.3°C |
| March | 25.0°C | 17.8°C |
| April | 29.5°C | 19.1°C |
| May | 34.6°C | 20.2°C |
| June | 40.1°C | 21.9°C |
| July | 40.9°C | 24.3°C |
| August | 40.0°C | 25.3°C |
| September | 37.2°C | 25.0°C |
| October | 31.1°C | 23.1°C |
| November | 24.3°C | 20.4°C |
| December | 18.4°C | 17.5°C |
Year at a glance
| Measure | Phoenix | San Diego |
|---|---|---|
| Mean annual temperature | 23.0°C | 17.0°C |
| Warmest month (avg high) | Jul · 41°C | Aug · 25°C |
| Coldest month (avg low) | Jan · 5°C | Jan · 9°C |
| Annual range (warmest high − coldest low) | 36°C | 17°C |
| Annual precipitation | 243.4 mm | 298.4 mm |
| Rainy days per year | 30 | 38 |
| Wettest / driest month | Feb / Jun | Feb / Jun |
| Average sunshine per day | 11.1 h | 10.9 h |
In short: Phoenix is the warmest overall (23.0°C mean); San Diego gets the most precipitation (298.4 mm a year); Phoenix is the sunniest (11.1 h a day on average); San Diego has the smallest swing between its warmest and coldest months.
Record high 1996–2025: Phoenix 47.7°C (2016-06-19), San Diego 36.6°C (2020-09-30). Record low: Phoenix -3.5°C (2007-01-14), San Diego 1.8°C (2007-01-15).
Source: Open-Meteo Historical Weather API (CC BY 4.0). Values are ERA5 reanalysis model data on a ~9–25 km grid, not readings from a weather station, so a single town’s thermometer can differ by a few degrees and local showers can be missed. Monthly means of daily ERA5 values, 1996–2025, for the grid cells nearest Phoenix (33.43, -112.03) and San Diego (32.72, -117.14).
Which months differ most?
The gap in average highs is widest in June, when Phoenix runs 33°F / 18°C warmer, and narrowest in December (2°F / 1°C apart). The biggest rainfall difference is in February: San Diego gets 1.3 in (32 mm) more on average.
Add a third or fourth city, or swap in any other place, in the full comparison tool. For one city in depth, see the Phoenix climate and San Diego climate pages.
Compare Phoenix or San Diego with another city
Questions people ask
Is Phoenix warmer than San Diego?
Phoenix is warmer on average: its mean annual temperature is 73°F (23°C) against 63°F (17°C) in San Diego (ERA5, 1996–2025).
Which gets more rain, Phoenix or San Diego?
San Diego, with about 11.7 in (298 mm) of precipitation a year and 38 days with at least 1 mm, compared with 9.6 in (243 mm) and 30 days in Phoenix.
Which is sunnier, Phoenix or San Diego?
Phoenix averages more sunshine: 11.1 h a day against 10.9 h. Sunshine duration is modelled from cloud cover.
How reliable is this comparison?
Both cities use the same 30-year reanalysis, so differences are consistent. Absolute values describe a grid cell several kilometres wide and can differ by a degree or two from the airport station.