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Pasadena, California climate
Csa Hot-summer Mediterranean
Pasadena has a mildly seasonal warm-temperate climate (Hot-summer Mediterranean, Köppen Csa). The hottest month is August with an average daily high near 33°C, while the coldest is December averaging around 7°C at night. Precipitation totals about 510 mm a year and is strongly seasonal — February alone averages 131 mm while August barely receives 1 mm.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresClear vs cloudy days
Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day countsPasadena climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 20 | 21 | 23 | 25 | 26 | 29 | 32 | 33 | 32 | 28 | 24 | 20 |
| Avg temp (°C) | 14 | 14 | 16 | 17 | 19 | 22 | 24 | 25 | 24 | 21 | 17 | 13 |
| Avg low (°C) | 8 | 8 | 9 | 10 | 12 | 14 | 17 | 17 | 16 | 14 | 10 | 7 |
| Precipitation (mm) | 115 | 131 | 77 | 28 | 12 | 5 | 2 | 1 | 6 | 21 | 28 | 85 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 20 | 21 | 23 | 25 | 26 | 29 |
| Avg temp (°C) | 14 | 14 | 16 | 17 | 19 | 22 |
| Avg low (°C) | 8 | 8 | 9 | 10 | 12 | 14 |
| Precipitation (mm) | 115 | 131 | 77 | 28 | 12 | 5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 32 | 33 | 32 | 28 | 24 | 20 |
| Avg temp (°C) | 24 | 25 | 24 | 21 | 17 | 13 |
| Avg low (°C) | 17 | 17 | 16 | 14 | 10 | 7 |
| Precipitation (mm) | 2 | 1 | 6 | 21 | 28 | 85 |
How often — frequency of weather events
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 8 | 6 | 3 | 3 | 2 | 0.6 | 0.4 | 0.8 | 3 | 3 | 6 |
| Days with high ≥ 32°C (days) | 0.0 | 0.4 | 0.9 | 3 | 3 | 6 | 15 | 19 | 16 | 8 | 2 | — |
| Days with low ≤ 0°C (days) | 0.0 | — | — | — | — | — | — | — | — | — | — | 0.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 7 | 8 | 6 | 3 | 3 | 2 |
| Days with high ≥ 32°C (days) | 0.0 | 0.4 | 0.9 | 3 | 3 | 6 |
| Days with low ≤ 0°C (days) | 0.0 | — | — | — | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Days with measurable rain (days) | 0.6 | 0.4 | 0.8 | 3 | 3 | 6 |
| Days with high ≥ 32°C (days) | 15 | 19 | 16 | 8 | 2 | — |
| Days with low ≤ 0°C (days) | — | — | — | — | — | 0.0 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 47 | 45 | 43 | 36 | 32 | 22 | 18 | 14 | 19 | 27 | 34 | 43 |
| Clear days (≤ 30% cloud) | 12 | 11 | 13 | 15 | 17 | 22 | 25 | 27 | 23 | 21 | 17 | 13 |
| Partly cloudy days (30–70%) | 11 | 9 | 11 | 10 | 10 | 6 | 5 | 3 | 5 | 7 | 9 | 11 |
| Cloudy days (≥ 70%) | 9 | 8 | 7 | 5 | 4 | 2 | 1 | 0.8 | 1 | 4 | 5 | 7 |
| Relative humidity (%) | 61 | 65 | 66 | 63 | 63 | 58 | 53 | 49 | 50 | 52 | 52 | 58 |
| Wind speed (m/s) | 2.4 | 2.3 | 2.2 | 2.2 | 2.1 | 1.9 | 1.8 | 1.8 | 1.7 | 1.9 | 2.1 | 2.4 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 47 | 45 | 43 | 36 | 32 | 22 |
| Clear days (≤ 30% cloud) | 12 | 11 | 13 | 15 | 17 | 22 |
| Partly cloudy days (30–70%) | 11 | 9 | 11 | 10 | 10 | 6 |
| Cloudy days (≥ 70%) | 9 | 8 | 7 | 5 | 4 | 2 |
| Relative humidity (%) | 61 | 65 | 66 | 63 | 63 | 58 |
| Wind speed (m/s) | 2.4 | 2.3 | 2.2 | 2.2 | 2.1 | 1.9 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 18 | 14 | 19 | 27 | 34 | 43 |
| Clear days (≤ 30% cloud) | 25 | 27 | 23 | 21 | 17 | 13 |
| Partly cloudy days (30–70%) | 5 | 3 | 5 | 7 | 9 | 11 |
| Cloudy days (≥ 70%) | 1 | 0.8 | 1 | 4 | 5 | 7 |
| Relative humidity (%) | 53 | 49 | 50 | 52 | 52 | 58 |
| Wind speed (m/s) | 1.8 | 1.8 | 1.7 | 1.9 | 2.1 | 2.4 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Pasadena (NOAA GHCN station USC00046719), inside the city.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.