Sunnyvale weather in October
In October, Sunnyvale has daytime highs averaging 24 °C, nights around 13 °C, with 2.9 wet days, and a sea temperature of 14 °C. Figures are 1991–2020 climate normals.
- 23.8°C Average high
- 13.4°C Average low
- 2.9days Wet days
- 29mm Rainfall
- 14.2°C Sea temperature
- 11h Daylight
Daily temperatures through October
How October develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 October | 25.1 °C | 14.2 °C | 6 % |
| 11–20 October | 24.4 °C | 13.8 °C | 8 % |
| 21–31 October | 22.3 °C | 12.5 °C | 13 % |
- Average highs fall from 25.1 °C early in October to 22.3 °C by the end of it.
- Rain is most likely over days 21–31 of October (13 % of days) and least likely over days 1–10 (6 %).
What to expect
| Measure | Typical October | Share of the month |
|---|---|---|
| Days above 25 °C | 12 of 31 | 38 % |
| Days above 30 °C | 3.1 of 31 | 10 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 2.9 of 31 | 9 % |
Conditions in October
| Measure | Average |
|---|---|
| Mean temperature | 17 °C |
| Record high (1991–2020) | 38 °C |
| Record low (1991–2020) | 5.0 °C |
| Relative humidity | 66 % |
| Wind speed | 12 km/h |
| Cloud cover | 31 % |
Where Sunnyvale ranks in October
| Ranking | Position | Value |
|---|---|---|
| Places with the best weather in North America in October | 1st of 50 | 97/100 |
| Places with the best weather in the world in October | 30th of 50 | 97/100 |
October compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| August | 27.7 °C | 1 mm | 22 % |
| September | 27.4 °C | 2 mm | 21 % |
| October | 23.8 °C | 29 mm | 31 % |
| November | 18.0 °C | 58 mm | 47 % |
| December | 14.2 °C | 116 mm | 55 % |
See all twelve months for Sunnyvale
- October is the 5th warmest month here.
- It is the 6th driest month of the year.
- It ranks 5th for least cloud cover.
- Days last about 11 hours from sunrise to sunset.
- It rains on 2.9 of 31 days — 9 % of the month.
- Nights are about 10 °C cooler than the middle of the day.
- The hottest October day on record since 1991 reached 38 °C, 14 °C above the usual daytime high.
- Beach score: 59 / 100 — see how this is calculated.
QuestionsOctober in Sunnyvale, answered
How warm is Sunnyvale in October?
Daily highs average 24 °C and nights fall to about 13 °C, a spread of 10 °C between afternoon and dawn. That makes October the 5th warmest month of the year here.
Does it rain much in Sunnyvale in October?
October averages 29 mm of rain, spread over about 3 of the 31 days — 9 % of the month. Cloud cover averages 31 % of the sky.
Is the sea warm enough to swim in October?
The sea averages 14 °C off Sunnyvale in October. Most people find water below 20 °C bracing and above 25 °C comfortable for a long swim; this figure is a monthly surface average, so a sheltered bay on a still afternoon can be warmer.
How long are the days in October?
Sunnyvale averages 11 hours between sunrise and sunset in October. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.