5-day weather forecast San Francisco Sep 18, 2026
18°Weather forecast San Francisco Friday Sep 18, 2026: sunny, temperature from 15 °C to 18 °C.
Precipitation probability 15%. Wind up to 7 m/s (gusts 8.81 m/s). Air humidity 74–90%, atmospheric pressure 763–764 mm Hg, UV index up to 6.7.
Weather Alerts
Small Craft Advisory issued September 15 at 8:42PM PDT until September 16 at 9:00PM PDT by NWS San Francisco CA
Small Craft Advisory
* WHAT...West winds 10 to 15 kt with gusts up to 25 kt and choppy
waters expected.
* WHERE...San Francisco Bay South of the Bay Bridge.
* WHEN...From 9 AM to 9 PM PDT Wednesday.
* IMPACTS...Conditions will be hazardous to small craft.
Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.
Small Craft Advisory issued September 15 at 2:17PM PDT until September 16 at 9:00PM PDT by NWS San Francisco CA
Small Craft Advisory
* WHAT...West winds 10 to 15 kt with gusts to 25 kt and choppy
waters expected.
* WHERE...San Francisco Bay South of the Bay Bridge.
* WHEN...From 9 AM to 9 PM PDT Wednesday.
* IMPACTS...Conditions will be hazardous to small craft.
Inexperienced mariners, especially those operating smaller
vessels, should avoid navigating in hazardous conditions.
5 days at a glance — tap a day to open it
Sunrise 06:54
Sunset 19:13
Sunset 19:13
First Quarter53% illuminated
Moonrise 15:01 · Moonset does not set today
Moonrise 15:01 · Moonset does not set today
Chart
Table
| Time | Weather | Temperature | Rain chance | Cloud cover | Humidity | Pressure | Wind | UV Index |
|---|---|---|---|---|---|---|---|---|
| 00:00 |  Clear | 16 °C | 12% | 0% | 86% | 764 mm Hg | W 279° 2.69 (4) m/s | 0 |
| 01:00 | Clear | 16 °C | 12% | 0% | 87% | 764 mm Hg | W 271° 2.39 (3.22) m/s | 0 |
| 02:00 | Clear | 15 °C | 12% | 1% | 88% | 764 mm Hg | W 271° 2.31 (3.03) m/s | 0 |
| 03:00 | Clear | 15 °C | 13% | 5% | 89% | 764 mm Hg | WSW 253° 1.81 (2.31) m/s | 0 |
| 04:00 | Clear | 15 °C | 13% | 4% | 90% | 764 mm Hg | WSW 247° 1.5 (1.92) m/s | 0 |
| 05:00 | Clear | 15 °C | 13% | 2% | 90% | 764 mm Hg | SW 216° 1.61 (1.81) m/s | 0 |
| 06:00 | Clear | 15 °C | 13% | 2% | 90% | 764 mm Hg | WSW 238° 1.19 (1.33) m/s | 0 |
| 07:00 | Sunny | 15 °C | 13% | 1% | 90% | 764 mm Hg | SSW 205° 1 (1) m/s | 0 |
| 08:00 | Sunny | 15 °C | 12% | 0% | 87% | 764 mm Hg | SSW 195° 1.31 (1.39) m/s | 0.3 |
| 09:00 | Sunny | 16 °C | 10% | 0% | 82% | 764 mm Hg | SW 234° 1.31 (5.31) m/s | 1.1 |
| 10:00 | Sunny | 17 °C | 9% | 0% | 79% | 764 mm Hg | WSW 244° 1.39 (5.39) m/s | 2.5 |
| 11:00 | Sunny | 17 °C | 8% | 0% | 76% | 764 mm Hg | WSW 252° 1.81 (5.81) m/s | 4.3 |
| 12:00 | Sunny | 18 °C | 7% | 3% | 74% | 764 mm Hg | WSW 255° 2.69 (5.69) m/s | 5.9 |
| 13:00 | Sunny | 18 °C | 8% | 12% | 75% | 764 mm Hg | WSW 257° 3.81 (8.81) m/s | 6.7 |
| 14:00 | Sunny | 17 °C | 9% | 19% | 76% | 764 mm Hg | W 259° 4.39 (4.5) m/s | 6.3 |
| 15:00 |  Partly cloudy | 17 °C | 11% | 29% | 78% | 764 mm Hg | W 262° 5 (6.31) m/s | 5 |
| 16:00 | Sunny | 17 °C | 10% | 16% | 78% | 763 mm Hg | W 268° 6.31 (7.81) m/s | 3.2 |
| 17:00 | Sunny | 17 °C | 10% | 14% | 79% | 763 mm Hg | W 272° 7 (8.61) m/s | 1.4 |
| 18:00 | Sunny | 16 °C | 11% | 14% | 82% | 763 mm Hg | W 276° 6.19 (8.42) m/s | 0.4 |
| 19:00 | Sunny | 16 °C | 12% | 15% | 85% | 763 mm Hg | W 276° 5.11 (7.14) m/s | 0 |
| 20:00 | Clear | 15 °C | 14% | 24% | 88% | 763 mm Hg | W 272° 4.69 (6.5) m/s | 0 |
| 21:00 | Clear | 15 °C | 14% | 21% | 88% | 763 mm Hg | W 263° 4.5 (6.61) m/s | 0 |
| 22:00 | Clear | 15 °C | 15% | 22% | 88% | 763 mm Hg | W 264° 5.11 (7) m/s | 0 |
| 23:00 | Clear | 15 °C | 14% | 21% | 89% | 763 mm Hg | W 266° 4.81 (6.69) m/s | 0 |
San Francisco on the map
Data Sources & Methodology
Our weather forecasts are powered by a professional weather data provider that aggregates data from national weather services, satellite observations, radar networks, and over 80,000 weather stations worldwide. Forecast data is updated multiple times daily. We convert raw data into clear summaries — wind speed in m/s, pressure in mmHg — so you can plan your day with confidence.