San Francisco is 4.1°C (7.4°F) warmer by day, San Francisco has 2.9°C (5.2°F) warmer nights, Seattle gets 636 mm (25 in) more rain a year.
San Francisco is at its warmest in September and coolest in January, while Seattle peaks in August and bottoms out in December. Month for month, San Francisco is the warmer of the two in 10 of 12 months.
Seattle is the wetter of the two, collecting 1,255 mm (49.4 in) of rain a year against 619 mm (24.4 in) in San Francisco. The most comfortable time to visit is July, August and September in San Francisco and July, August and September in Seattle.
| San Francisco | Metric | Seattle |
|---|---|---|
| 🌡️ Temperature | ||
| 65.8°F | 🌡️Average daytime high | 58.5°F |
| 49.1°F | 🌙Average nighttime low | 43.9°F |
| September | 🔥Hottest month | August |
| January | ❄️Coldest month | December |
| 🌧️ Rain | ||
| 24.4 in | 🌧️Annual rainfall | 49.4 in |
| December | ☔Wettest month | November |
| July | 🏜️Driest month | July |
| 💨 Climate | ||
| 77% | 💧Average humidity | 83% |
| 2.3 m/s | 💨Average wind speed | 0.7 m/s |
Overnight, San Francisco typically falls to around 9.5°C (49.1°F) while Seattle settles near 6.6°C (43.9°F).
San Francisco is hottest in September and coldest in January, whereas Seattle peaks in August and is coolest in December.
San Francisco sees the most rain in December and the least in July; Seattle is wettest in November and driest in July.
Seattle feels the more humid of the two, averaging 83% relative humidity against 77%.
For Seattle, the pick of the year is July, August and September.
Month by month, here is the coldest night, the average day and the hottest afternoon each city can expect. Switch Compare to read rainfall, humidity, wind or solar instead, and Period to move between the long-term 45-year average and any single year — the shading is a quick warm-to-cool guide.
| Month | San Francisco | Seattle | ||||
|---|---|---|---|---|---|---|
| Min | Avg | Max | Min | Avg | Max | |
| January | 43.3 | 49.8❄️ | 56.3 | 35.1 | 40.1 | 45 |
| February | 44.6 | 51.3 | 57.9 | 34.9 | 41 | 47.1 |
| March | 46 | 52.9 | 59.9 | 37.8 | 44.8 | 51.6 |
| April | 47.1 | 55 | 63 | 40.8 | 48.6 | 56.5 |
| May | 49.6 | 58.3 | 66.9 | 46.2 | 54.7 | 63 |
| June | 52 | 61.7 | 71.2 | 50.7 | 59.2 | 67.6 |
| July | 53.6 | 63.3 | 73 | 55 | 64.2 | 73.2 |
| August | 54.9 | 64.8 | 74.5 | 55.8 | 64.9🔥 | 74.3 |
| September | 55.2 | 65.3🔥 | 75.4 | 51.4 | 60.4 | 69.4 |
| October | 52.9 | 62.2 | 71.6 | 45 | 52.2 | 59.5 |
| November | 47.7 | 55.2 | 62.8 | 38.8 | 44.2 | 49.6 |
| December | 43.5 | 50 | 56.5 | 34.3 | 39❄️ | 43.7 |
| Annual Avg | 49.3 | 57.6 | 65.7 | 43.9 | 51.1 | 58.5 |
Min / mean / max temperature (°F). 🔥 marks each city's hottest month, ❄️ its coldest; shading runs cool blue to warm red.
The same figures plotted out, so the shape of a typical year is easier to see than in a grid. Where the two lines run close together San Francisco and Seattle feel alike; where they separate, they are genuinely different places to be.
Hover or tap any point to read the exact figures. San Francisco Seattle
See how San Francisco and Seattle stack up against other cities. Swipe for more.
Choose which city to keep, then search for any other city in our database — we'll build the comparison for you.
Quick answers to the questions people ask most when comparing San Francisco and Seattle — each drawn straight from the climate figures above.
San Francisco is the warmer of the two. It averages daytime highs of 18.8°C (65.8°F) against 14.7°C (58.5°F) in Seattle — roughly 4.1°C (7.4°F) warmer by day. Nights are milder in San Francisco, with average lows of 9.5°C (49.1°F) versus 6.6°C (43.9°F).
San Francisco is hottest in September, averaging highs of about 24.1°C (75.4°F), while Seattle peaks in August at around 23.5°C (74.3°F). That makes San Francisco the hotter of the two at the height of summer.
Seattle gets colder. In its coldest month (December) overnight lows average about 1.3°C (34.4°F), compared with 6.3°C (43.3°F) at the low point of the year in San Francisco.
Seattle is the wetter city, collecting about 1,255 mm (49.4 in) of rain a year versus 619 mm (24.4 in) in San Francisco. San Francisco is wettest in December and driest in July; Seattle is wettest in November and driest in July.
Seattle is the more humid of the two, averaging 83% relative humidity over the year against 77% in San Francisco.
The most comfortable months in San Francisco are July, August and September, when average temperatures are at their mildest.
Seattle is at its most pleasant around July, August and September, based on the mildest average temperatures of the year.
San Francisco is the warmer city in 10 of the 12 months of the year. The gap is widest in November, about 6.1°C (11°F), and narrowest in August, about 0.1°C (0.2°F).
Seattle has the bigger seasonal swing, about 14.4°C (25.9°F) between its coldest and hottest months versus 8.6°C (15.5°F) in San Francisco — so San Francisco has the steadier, more even climate.
On climate alone, San Francisco comes out ahead — it offers warmer days, less rain and lower humidity than Seattle. Seattle is the better fit only if you'd actually prefer cooler weather, more rainfall and a more humid climate.
Every figure on this page is calculated from NASA POWER satellite climate data spanning 1981–2025 (45 years). The averages describe the long-term climate of San Francisco and Seattle, not a single year's weather or a short-range forecast.
