April is one of the cooler months of the year in Boulder, with average highs near 16.1°C and lows around 0.7°C (mean 8.4°C). It is a relatively wet time of year, averaging 54 mm of rainfall and 50% relative humidity across the period.
April is one of the cooler months of the year in Boulder. Across 45 years of records, the warmest Aprils in Boulder were 1981 and 2012 — when the month averaged 12°C — while the coldest was 1983 at 4°C. Typical April days reach 16.1°C with nights near 0.7°C. The long-term April temperature trend is broadly flat.
April is a relatively wet time of year in Boulder, averaging 54 mm of rainfall. The wettest April on record was 1999 with 160 mm, while the driest was 2002 at 8 mm.
Relative humidity in Boulder during April averages 50%. The most humid April was 1983 at 61%, and the least humid was 2022 at 37%.
April receives about 5.5 kWh/m²/day of solar energy in Boulder. The sunniest Aprils were 2008 and 2023 at 6.2 kWh/m²/day, and the cloudiest was 2016 at 4.9.
Average wind speed in Boulder during April is 2.7 m/s. The windiest April was 1996 at 3.2 m/s, while the calmest were 1992 and 1998 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 8.4°C | 7.5°C | 9.2°C | 8.5°C | 8.5°C | +0.1°C |
| Avg High | 16.1°C | 14.7°C | 17.1°C | 16.2°C | 16.6°C | +0.5°C |
| Avg Low | 0.8°C | 0.2°C | 1.2°C | 0.8°C | 0.4°C | -0.4°C |
| Avg Rain | 47 mm | 68 mm | 52 mm | 56 mm | 40 mm | -7 mm |
April temperatures in Boulder have risen by about 1°C between 1981–1985 and 2021–2025.
April has ranged from a record low of -13.7°C (2020) to a record high of 30.2°C (2012).
Rainfall in April is a relatively wet time of year, averaging 54 mm, with a wettest year of 160 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.2°C per decade while lows rose 0°C per decade, widening the gap between day and night.
A good time to visit Boulder
April is a good time to visit Boulder, with days averaging 16.1°C and nights around 0.7°C (mean 8.4°C, cooler than Boulder'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 | 17.9°C | 9.7°C | 1.4°C | 28.9°C | -6.1°C | 29 mm | 46% | 2.4 m/s | 5.6 |
| 2024 | 17.6°C | 9.7°C | 1.8°C | 26.2°C | -4.4°C | 66 mm | 49% | 2.9 m/s | 5.6 |
| 2023 | 16.1°C | 8.1°C | 0.1°C | 27.7°C | -8.0°C | 35 mm | 45% | 2.5 m/s | 6.2 |
| 2022 | 17.1°C | 8.8°C | 0.4°C | 28.4°C | -6.9°C | 14 mm | 37% | 3.1 m/s | 5.9 |
| 2021 | 15.2°C | 7.1°C | -0.9°C | 25.3°C | -8.3°C | 56 mm | 50% | 2.5 m/s | 5.7 |
| 2020 | 15.4°C | 7.6°C | -0.2°C | 28.3°C | -13.7°C | 40 mm | 50% | 2.4 m/s | 5.9 |
| 2019 | 16.7°C | 9.1°C | 1.5°C | 25.7°C | -7.5°C | 44 mm | 53% | 2.3 m/s | 5.1 |
| 2018 | 16.9°C | 8.7°C | 0.5°C | 26.9°C | -5.4°C | 34 mm | 45% | 2.9 m/s | 5.5 |
| 2017 | 16.6°C | 8.8°C | 1.0°C | 26.0°C | -7.3°C | 54 mm | 49% | 2.5 m/s | 5.6 |
| 2016 | 14.7°C | 7.8°C | 0.8°C | 24.7°C | -5.5°C | 74 mm | 57% | 2.6 m/s | 4.9 |
| 2015 | 16.7°C | 8.9°C | 1.1°C | 25.1°C | -3.7°C | 76 mm | 51% | 2.3 m/s | 5.2 |
| 2014 | 15.8°C | 8.3°C | 0.9°C | 25.3°C | -8.4°C | 38 mm | 50% | 2.9 m/s | 5.5 |
| 2013 | 12.9°C | 5.1°C | -2.7°C | 25.5°C | -11.4°C | 68 mm | 54% | 2.7 m/s | 5 |
| 2012 | 20.3°C | 12.0°C | 3.6°C | 30.2°C | -1.5°C | 33 mm | 41% | 2.6 m/s | 6 |
| 2011 | 15.5°C | 7.9°C | 0.3°C | 24.9°C | -5.3°C | 55 mm | 49% | 3 m/s | 5.2 |
| 2010 | 15.6°C | 8.1°C | 0.7°C | 24.7°C | -4.5°C | 81 mm | 52% | 2.9 m/s | 5.3 |
| 2009 | 15.0°C | 7.6°C | 0.1°C | 25.1°C | -8.6°C | 101 mm | 55% | 2.9 m/s | 5.4 |
| 2008 | 15.8°C | 7.5°C | -0.7°C | 25.8°C | -8.1°C | 28 mm | 42% | 3 m/s | 6.2 |
| 2007 | 15.7°C | 8.0°C | 0.4°C | 27.6°C | -6.6°C | 63 mm | 54% | 2.7 m/s | 5.3 |
| 2006 | 19.6°C | 11.2°C | 2.9°C | 27.9°C | -4.9°C | 20 mm | 39% | 2.8 m/s | 6 |
| 2005 | 16.1°C | 8.4°C | 0.7°C | 24.6°C | -6.7°C | 67 mm | 52% | 2.8 m/s | 5.4 |
| 2004 | 15.7°C | 8.6°C | 1.4°C | 26.0°C | -7.1°C | 82 mm | 54% | 2.6 m/s | 5 |
| 2003 | 17.4°C | 9.8°C | 2.2°C | 25.5°C | -5.0°C | 62 mm | 49% | 2.6 m/s | 5.2 |
| 2002 | 19.7°C | 10.8°C | 1.9°C | 27.9°C | -7.4°C | 8 mm | 37% | 2.7 m/s | 5.7 |
| 2001 | 17.9°C | 9.8°C | 1.7°C | 26.1°C | -4.6°C | 48 mm | 48% | 2.5 m/s | 5.1 |
| 2000 | 18.5°C | 9.9°C | 1.4°C | 25.3°C | -7.5°C | 39 mm | 45% | 2.9 m/s | 5.5 |
| 1999 🌧️ | 12.7°C | 5.9°C | -0.8°C | 22.4°C | -9.2°C | 160 mm | 57% | 3.1 m/s | 5.2 |
| 1998 | 13.4°C | 6.5°C | -0.5°C | 25.0°C | -4.6°C | 71 mm | 57% | 2.2 m/s | 5.8 |
| 1997 | 11.9°C | 5.0°C | -2.0°C | 23.4°C | -11.3°C | 87 mm | 57% | 2.5 m/s | 5.5 |
| 1996 | 16.0°C | 8.4°C | 0.9°C | 25.7°C | -5.0°C | 34 mm | 47% | 3.2 m/s | 5.3 |
| 1995 | 13.0°C | 6.1°C | -0.8°C | 21.9°C | -6.9°C | 97 mm | 56% | 2.5 m/s | 5.6 |
| 1994 | 15.1°C | 7.9°C | 0.7°C | 26.6°C | -6.8°C | 59 mm | 55% | 2.6 m/s | 5.1 |
| 1993 | 14.2°C | 7.1°C | -0.1°C | 23.1°C | -5.1°C | 63 mm | 56% | 2.4 m/s | 5.4 |
| 1992 | 19.2°C | 11.3°C | 3.4°C | 28.5°C | -5.2°C | 26 mm | 48% | 2.2 m/s | 5.6 |
| 1991 | 15.3°C | 7.8°C | 0.2°C | 27.0°C | -7.5°C | 46 mm | 48% | 2.4 m/s | 5.5 |
| 1990 | 16.0°C | 8.7°C | 1.4°C | 24.9°C | -6.4°C | 42 mm | 56% | 2.5 m/s | 5 |
| 1989 | 17.3°C | 9.5°C | 1.7°C | 29.5°C | -11.2°C | 36 mm | 45% | 2.8 m/s | 5.4 |
| 1988 | 17.6°C | 9.4°C | 1.2°C | 27.2°C | -8.0°C | 30 mm | 48% | 2.5 m/s | 5.6 |
| 1987 | 17.9°C | 10.0°C | 2.1°C | 27.2°C | -6.1°C | 34 mm | 47% | 2.9 m/s | 6 |
| 1986 | 16.2°C | 8.7°C | 1.2°C | 24.7°C | -7.0°C | 81 mm | 56% | 2.7 m/s | 5.1 |
| 1985 | 17.7°C | 9.9°C | 2.1°C | 26.5°C | -4.7°C | 55 mm | 48% | 2.6 m/s | 5.4 |
| 1984 | 12.3°C | 5.3°C | -1.7°C | 23.4°C | -5.3°C | 69 mm | 57% | 3.1 m/s | 5.5 |
| 1983 ❄️ | 10.2°C | 4.0°C | -2.2°C | 22.5°C | -12.6°C | 64 mm | 61% | 2.4 m/s | — |
| 1982 | 15.2°C | 7.2°C | -0.9°C | 23.2°C | -6.3°C | 23 mm | 42% | 3 m/s | — |
| 1981 🔥 | 20.3°C | 12.0°C | 3.6°C | 28.8°C | -5.3°C | 28 mm | 42% | 2.3 m/s | — |
Actual recorded April data for each year, 1981–2025 — sourced from NASA POWER.
The average high in April is around 16.1°C with lows near 0.7°C (mean 8.4°C), based on 45 years of NASA POWER data.
April averages 54 mm of rainfall in Boulder, a relatively wet time of year. The wettest on record was 160 mm in 1999.
The hottest April reached 30.2°C in 2012. The coldest dipped to -13.7°C in 2020.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average April temperatures have risen by about 1°C. Daytime highs moved from 15.1°C to 16.8°C and overnight lows from 0.2°C to 0.6°C over the same span.
April is one of the cooler months of the year in Boulder and a relatively wet time of year, so plan for around 16.1°C daytime highs and 0.7°C at night.
Not quite — April is the 6th coolest month in Boulder, averaging 8.4°C.
For April in Boulder, pack warm layers and a jacket for chilly mornings, with typical highs of 16.1°C and lows of 0.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in April averages 50% — relatively dry.
Average wind speed in April is 2.7 m/s. The windiest April on record averaged 3.2 m/s (1996).
The wettest April on record was 1999 with 160 mm. On average, April sees 54 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 Boulder 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.
