Boulder has a temperate climate with warm summers and freezing winters.
Temperatures peak in July and drop to their lowest in January, while rainfall is highest during spring and early summer months.
Humidity remains relatively low throughout the year, especially during winter months, creating cold and dry conditions.
| Month | 🌤️ | Avg High | Avg Temp | Avg Low | Record High | Record Low | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|---|---|
| January | 🌨️ | 42.1°F | 32.0°F | 21.9°F | 68.4°F | -11.4°F | 56% | 21 | 2.9 | 2.51 |
| February | 🌨️ | 44.8°F | 33.6°F | 22.4°F | 68.2°F | -16.2°F | 56% | 23 | 2.8 | 3.54 |
| March | 🌨️ | 53.2°F | 40.4°F | 27.5°F | 80.8°F | 0.1°F | 52% | 41 | 2.7 | 4.65 |
| April | 🌨️ | 61.0°F | 47.1°F | 33.3°F | 86.4°F | 7.3°F | 50% | 54 | 2.7 | 5.47 |
| May | 🌤️ | 70.6°F | 56.6°F | 42.6°F | 94.3°F | 17.1°F | 50% | 68 | 2.3 | 6.02 |
| June | ☀️ | 83.2°F | 68.2°F | 53.3°F | 103.8°F | 36.0°F | 43% | 47 | 2.2 | 6.91 |
| July | 🌞 | 88.7°F | 74.6°F | 60.4°F | 102.0°F | 46.4°F | 42% | 53 | 2.2 | 6.54 |
| August | 🌞 | 86.3°F | 72.7°F | 59.1°F | 102.2°F | 43.0°F | 44% | 47 | 2.1 | 5.76 |
| September | ☀️ | 78.9°F | 64.6°F | 50.3°F | 98.8°F | 17.6°F | 43% | 36 | 2.1 | 5.00 |
| October | 🌤️ | 65.3°F | 51.6°F | 38.0°F | 88.3°F | 6.6°F | 47% | 31 | 2.2 | 3.71 |
| November | 🌨️ | 52.0°F | 40.2°F | 28.5°F | 77.9°F | -4.9°F | 52% | 26 | 2.4 | 2.58 |
| December | 🌨️ | 42.2°F | 32.2°F | 22.3°F | 73.8°F | -13.2°F | 57% | 22 | 2.6 | 2.15 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Pack heavy layers and prepare for snow — this is a Severe Winter destination.
🌤️ Early mornings and evenings are most comfortable during this Hot Summer season.
☔ Rainfall is spread across the year with no sharply defined wet season.
Monthly averages · 1981–2025 climate normals · °F
Temperatures rise steadily from spring, peak in July, and gradually decline through autumn into winter.
These seasonal patterns make summer ideal for outdoor activities, while winters bring freezing conditions and heavy snowfall.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Rainfall is concentrated in the spring and early summer months. Humidity stays relatively low (around 49%), peaking during winter months, which creates cold and dry conditions.
☔ Rainfall is spread across the year with no sharply defined wet season.
Monthly averages · 1981–2025
Across 45 years of records, Boulder's temperature shows a slight warming trend over the past decade. Its hottest day reached 103.8°F in June 2012, and its coldest dropped to -16.3°F in February 1989. 2012 was the warmest year overall and 1983 the coolest.
The warmest year in Boulder's recorded history was 2012 (avg: 54.1°F), while the coldest was 1983 (avg: 48.4°F).
Average annual high/low · Last 30 years · °F
Total annual precipitation · Last 30 years · mm/year
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|---|---|
2025 🔥 | 67.5°F | 53.8°F | 40.3°F | 101.3°F | -1.1°F | 427 | 46% | 2.4 m/s |
2024 | 67.3°F | 54.0°F | 40.6°F | 102.0°F | -11.4°F | 408 | 46% | 2.4 m/s |
2023 | 63.9°F | 51.3°F | 38.7°F | 100.0°F | -1.7°F | 542 | 50% | 2.3 m/s |
2022 | 64.9°F | 51.6°F | 38.3°F | 101.1°F | -7.6°F | 403 | 46% | 2.6 m/s |
2021 | 65.7°F | 52.5°F | 39.4°F | 100.6°F | -7.6°F | 441 | 47% | 2.4 m/s |
2020 | 65.8°F | 52.3°F | 39.0°F | 99.9°F | 3.9°F | 338 | 45% | 2.5 m/s |
2019 | 63.3°F | 50.4°F | 37.4°F | 99.5°F | 4.3°F | 482 | 51% | 2.3 m/s |
2018 | 65.1°F | 52.0°F | 38.8°F | 102.0°F | 2.8°F | 369 | 48% | 2.4 m/s |
2017 | 65.7°F | 52.3°F | 39.2°F | 98.4°F | -9.6°F | 472 | 50% | 2.4 m/s |
2016 | 65.5°F | 52.5°F | 39.4°F | 99.9°F | -1.7°F | 393 | 48% | 2.4 m/s |
Showing 1 to 10 of 45 years
Based on 45 years of data (1981–2025), July is typically the hottest month in Boulder, Colorado, with average high temperatures around 88.7°F.
January is the coldest month in Boulder, with average low temperatures around 21.9°F.
May receives the most rainfall with approximately 68 mm, while January is the driest with 21 mm.
The highest recorded temperature was 103.8°F in June 2012. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was -16.3°F in February 1989.
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
Boulder receives the most sunlight in June with an average solar radiation of 6.91 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning and agriculture in Colorado.
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.
