Last updated: June 24, 2025
In April, the average temperature in Boulder, United States hovers around 1°C (34°F). While you might experience a chilly minimum of -21°C (-6°F), daytime highs can reach up to 22°C (71°F). Expect 68 mm (2.7 in) of precipitation spread over 13 days, contributing to an average humidity level of 78%. Stay prepared for a mix of chilly and mild weather!
In April in Boulder, the average temperature is 1°C (34°F). Maximums can reach 22°C (71°F), and minimums can drop as low as -21°C (-6°F). Travelers should be prepared for a wide range of weather conditions and pack accordingly.
In Boulder in April, the precipitation amount is 68 mm (2.7 in) spread over 13 days.
In Boulder in April, humidity is 78%. With an average temperature of 1°C (34°F), this humidity feels like an extra layer of chill in the air, making travel uncomfortable and damp, often leading to a persistent sense of cold that can seep into your bones, leaving you wishing for a warm shelter.
In Boulder in April, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Boulder.
UV Risk Categories
Weather in Boulder varies notably across the year, with each month offering distinct climate conditions. This page compares April’s weather to other months in Boulder, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (18°F) | 23 mm (0.9 inches) | 87% | moderate |
| February Weather | -9°C (16°F) | 55 mm (2.2 inches) | 88% | moderate |
| March Weather | -2°C (28°F) | 40 mm (1.6 inches) | 83% | high |
| April Weather | 1°C (34°F) | 68 mm (2.7 inches) | 78% | very high |
| May Weather | 8°C (46°F) | 92 mm (3.6 inches) | 76% | very high |
| June Weather | 14°C (57°F) | 112 mm (4.4 inches) | 78% | extreme |
| July Weather | 18°C (65°F) | 44 mm (1.7 inches) | 77% | very high |
| August Weather | 17°C (64°F) | 39 mm (1.5 inches) | 71% | very high |
| September Weather | 12°C (54°F) | 43 mm (1.7 inches) | 68% | very high |
| October Weather | 3°C (38°F) | 44 mm (1.7 inches) | 72% | moderate |
| November Weather | -3°C (28°F) | 34 mm (1.3 inches) | 84% | moderate |
| December Weather | -8°C (19°F) | 32 mm (1.3 inches) | 90% | low |