April is one of the cooler months of the year in Sunnyvale, with average highs near 18.9°C and lows around 6.4°C (mean 12.6°C). It is one of the drier months, averaging 35 mm of rainfall and 78% relative humidity across the period.
April is one of the cooler months of the year in Sunnyvale. Across 45 years of records, the warmest Aprils in Sunnyvale were 1987 and 1990 — when the month averaged 15.2°C — while the coldest were 1983 and 2003 at 10.3°C. Typical April days reach 18.9°C with nights near 6.4°C. The long-term April temperature trend is broadly flat.
April is one of the drier months in Sunnyvale, averaging 35 mm of rainfall. The wettest April on record was 1983 with 104 mm, while the driest was 2021 at 2 mm.
Relative humidity in Sunnyvale during April averages 78%. The most humid April was 2006 at 86%, and the least humid was 1987 at 67%.
April receives about 6 kWh/m²/day of solar energy in Sunnyvale. The sunniest April was 2022 at 6.8 kWh/m²/day, and the cloudiest was 2006 at 4.7.
Average wind speed in Sunnyvale during April is 2.1 m/s. The windiest April was 1999 at 2.6 m/s, while the calmest was 1989 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.8°C | 12.6°C | 12.2°C | 12.9°C | 12.9°C | +0.1°C |
| Avg High | 19.2°C | 18.7°C | 18.2°C | 19.0°C | 19.2°C | 0°C |
| Avg Low | 6.3°C | 6.5°C | 6.1°C | 6.8°C | 6.5°C | +0.2°C |
| Avg Rain | 36 mm | 31 mm | 37 mm | 42 mm | 24 mm | -12 mm |
April temperatures in Sunnyvale have risen by about 0.7°C between 1981–1985 and 2021–2025.
April has ranged from a record low of -0.8°C (1999) to a record high of 33.5°C (1981).
Rainfall in April is one of the drier months, averaging 35 mm, with a wettest year of 104 mm.
A good time to visit Sunnyvale
April is a good time to visit Sunnyvale, with days averaging 18.9°C and nights around 6.4°C (mean 12.6°C, cooler than Sunnyvale's yearly average) and moderate rainfall. August and July are marginally more temperate, but April still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 19.0°C | 12.9°C | 6.8°C | 24.9°C | 4.2°C | 12 mm | 81% | 2 m/s | 5.6 |
| 2024 | 18.5°C | 12.6°C | 6.7°C | 25.6°C | 3.5°C | 39 mm | 83% | 2 m/s | 6.2 |
| 2023 | 17.7°C | 11.6°C | 5.5°C | 28.6°C | 0.4°C | 4 mm | 81% | 2.1 m/s | 6.6 |
| 2022 | 19.8°C | 13.0°C | 6.2°C | 32.2°C | 2.0°C | 38 mm | 73% | 2.5 m/s | 6.8 |
| 2021 | 20.6°C | 13.5°C | 6.3°C | 28.7°C | 3.8°C | 2 mm | 73% | 2.5 m/s | 6.2 |
| 2020 | 19.8°C | 13.6°C | 7.3°C | 28.8°C | 1.9°C | 47 mm | 78% | 2.1 m/s | 5.7 |
| 2019 | 19.7°C | 13.9°C | 8.1°C | 28.2°C | 5.3°C | 13 mm | 83% | 2 m/s | 5.7 |
| 2018 | 18.8°C | 12.5°C | 6.3°C | 27.1°C | 2.8°C | 58 mm | 80% | 2 m/s | 6 |
| 2017 | 18.0°C | 12.5°C | 7.1°C | 24.3°C | 3.2°C | 68 mm | 82% | 2.1 m/s | 5.8 |
| 2016 | 19.2°C | 13.6°C | 7.9°C | 28.6°C | 4.4°C | 40 mm | 80% | 2.1 m/s | 6.1 |
| 2015 | 20.1°C | 13.4°C | 6.7°C | 30.9°C | 3.3°C | 31 mm | 74% | 2.3 m/s | 6.4 |
| 2014 | 21.1°C | 14.3°C | 7.5°C | 32.9°C | 4.6°C | 29 mm | 75% | 2.1 m/s | 6.1 |
| 2013 | 22.1°C | 14.6°C | 7.0°C | 31.1°C | 2.4°C | 14 mm | 70% | 2.4 m/s | 6.5 |
| 2012 | 19.0°C | 12.8°C | 6.7°C | 30.6°C | 0.7°C | 67 mm | 79% | 2.2 m/s | 6 |
| 2011 | 16.4°C | 10.9°C | 5.3°C | 26.5°C | 1.7°C | 10 mm | 83% | 2.3 m/s | 6.1 |
| 2010 | 15.9°C | 10.5°C | 5.1°C | 23.8°C | 1.8°C | 96 mm | 83% | 2.1 m/s | 5.8 |
| 2009 | 18.6°C | 12.3°C | 6.0°C | 32.9°C | 0.5°C | 14 mm | 74% | 2.3 m/s | 6.4 |
| 2008 | 19.2°C | 12.0°C | 4.9°C | 29.6°C | 0.5°C | 3 mm | 73% | 2.3 m/s | 6.7 |
| 2007 | 20.0°C | 13.3°C | 6.6°C | 31.7°C | 2.8°C | 28 mm | 73% | 2.3 m/s | 6.2 |
| 2006 | 16.7°C | 11.9°C | 7.0°C | 25.0°C | 2.5°C | 101 mm | 86% | 2 m/s | 4.7 |
| 2005 | 17.4°C | 11.6°C | 5.8°C | 23.1°C | 1.6°C | 43 mm | 81% | 2.1 m/s | 6.3 |
| 2004 | 21.0°C | 14.1°C | 7.2°C | 33.2°C | 3.9°C | 4 mm | 73% | 2.1 m/s | 6.2 |
| 2003 | 15.3°C | 10.3°C | 5.2°C | 23.8°C | 2.4°C | 94 mm | 82% | 2.1 m/s | 5.6 |
| 2002 | 18.3°C | 12.4°C | 6.6°C | 27.1°C | 2.0°C | 9 mm | 80% | 2.1 m/s | 5.4 |
| 2001 | 16.8°C | 10.9°C | 5.0°C | 28.0°C | 0.7°C | 44 mm | 80% | 2.2 m/s | 6.1 |
| 2000 | 19.0°C | 13.0°C | 7.0°C | 25.7°C | 3.6°C | 34 mm | 81% | 2.1 m/s | 5.9 |
| 1999 | 17.0°C | 11.1°C | 5.3°C | 27.2°C | -0.8°C | 45 mm | 78% | 2.6 m/s | 6.1 |
| 1998 | 16.7°C | 11.3°C | 5.9°C | 27.4°C | 2.1°C | 50 mm | 83% | 1.9 m/s | 5.9 |
| 1997 | 19.9°C | 13.2°C | 6.5°C | 25.4°C | 1.6°C | 13 mm | 77% | 2.4 m/s | 6.2 |
| 1996 | 19.6°C | 13.5°C | 7.3°C | 28.2°C | 4.6°C | 43 mm | 80% | 2 m/s | 6.2 |
| 1995 | 16.5°C | 11.2°C | 6.0°C | 23.4°C | 2.1°C | 64 mm | 84% | 2.2 m/s | 5.8 |
| 1994 | 19.9°C | 13.4°C | 6.9°C | 28.2°C | 3.6°C | 39 mm | 76% | 2.1 m/s | 5.8 |
| 1993 | 17.7°C | 12.0°C | 6.3°C | 24.1°C | 1.3°C | 17 mm | 82% | 2 m/s | 6.4 |
| 1992 | 20.3°C | 14.0°C | 7.8°C | 27.6°C | 3.8°C | 10 mm | 80% | 1.9 m/s | 6 |
| 1991 | 17.5°C | 11.3°C | 5.1°C | 24.5°C | 1.8°C | 13 mm | 78% | 2.3 m/s | 6.3 |
| 1990 | 22.3°C | 15.2°C | 8.2°C | 28.8°C | 4.8°C | 13 mm | 72% | 2.3 m/s | 5.7 |
| 1989 | 21.2°C | 14.5°C | 7.8°C | 28.8°C | 4.7°C | 16 mm | 76% | 1.7 m/s | 5.8 |
| 1988 | 20.6°C | 13.8°C | 7.1°C | 31.9°C | 3.4°C | 51 mm | 69% | 2.1 m/s | 5.6 |
| 1987 🔥 | 23.2°C | 15.2°C | 7.3°C | 30.1°C | 3.1°C | 10 mm | 67% | 1.9 m/s | 6.1 |
| 1986 | 17.4°C | 11.5°C | 5.6°C | 26.8°C | 2.9°C | 20 mm | 80% | 2 m/s | 6 |
| 1985 | 21.4°C | 14.3°C | 7.2°C | 29.7°C | 3.9°C | 8 mm | 73% | 2.1 m/s | 5.7 |
| 1984 | 17.7°C | 11.5°C | 5.3°C | 28.8°C | 1.6°C | 20 mm | 75% | 2.5 m/s | 6.3 |
| 1983 ❄️ 🌧️ | 15.3°C | 10.3°C | 5.3°C | 21.3°C | 0.1°C | 104 mm | 82% | 2.1 m/s | — |
| 1982 | 16.4°C | 10.8°C | 5.2°C | 23.7°C | 1.9°C | 82 mm | 82% | 2.1 m/s | — |
| 1981 | 19.9°C | 13.1°C | 6.3°C | 33.5°C | 3.0°C | 12 mm | 75% | 2.1 m/s | — |
Actual recorded April data for each year, 1981–2025 — sourced from NASA POWER.
The average high in April is around 18.9°C with lows near 6.4°C (mean 12.6°C), based on 45 years of NASA POWER data.
April averages 35 mm of rainfall in Sunnyvale, one of the drier months. The wettest on record was 104 mm in 1983.
The hottest April reached 33.5°C in 1981. The coldest dipped to -0.8°C in 1999.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average April temperatures have risen by about 0.7°C. Daytime highs moved from 18.1°C to 19.1°C and overnight lows from 5.9°C to 6.3°C over the same span.
April is one of the cooler months of the year in Sunnyvale and one of the drier months, so plan for around 18.9°C daytime highs and 6.4°C at night.
Not quite — April is the 6th coolest month in Sunnyvale, averaging 12.6°C.
For April in Sunnyvale, pack warm layers and a jacket for chilly mornings, with typical highs of 18.9°C and lows of 6.4°C.
Relative humidity in April averages 78% — quite humid.
Average wind speed in April is 2.1 m/s. The windiest April on record averaged 2.6 m/s (1999).
The wettest April on record was 1983 with 104 mm. On average, April sees 35 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Sunnyvale behaves each April, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for April specifically, along with year-by-year records and how the month has changed over the decades.
