Longmont (CO) Temperature by Month
Longmont in Colorado, United States of America sees significant seasonal temperature differences, with daytime highs between 6°C (43°F) in December and 32°C (90°F) in July, averaging 19°C (66°F) annually. Explore the full monthly breakdown below.
Longmont Monthly Temperatures
The climate in Longmont is dynamic, ranging widely from chilly in winter to very warm in summer. Nights are significantly colder, with lows dropping from 14°C (57°F) in July to -10°C (14°F) in December.
The chart below illustrates the average maximum day and minimum night temperatures in Longmont by month:
The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. July, the warmest month, gets 323 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Longmont vs the United States of America
The map below shows the annual temperature across the United States of America. You can also select individual months if you want to compare a specific time of year.
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Longmont vs World: Temperature Compared
Longmont's average annual maximum temperature is 19°C (66°F). To put that in context, here's how it compares to a few well-known destinations:
Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.
Glasgow, Scotland averages 13°C (55°F) a year — mild but often grey, with cold winters and rarely hot summers.
Osaka, Japan averages 22°C (72°F) annually, with hot humid summers, mild winters, and pleasant spring and autumn seasons.
Melbourne, Australia averages 20°C (68°F) annually — known for unpredictable weather, with four seasons sometimes happening in one day.
What Does the Temperature Feel Like in Longmont?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Longmont, December is the coolest month, with average highs of 6°C (43°F) and humidity around 56% — considered moderate. In July, the warmest month, temperatures average 32°C (90°F) with 46% humidity — conditions that feel moderate. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
Seasonal temperature shifts influence more than just how warm it feels — they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.
Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Longmont this rarely lasts long on the ground.
For more on Longmont's weather — including monthly rainfall, sunshine hours, and humidity — visit our Longmont climate page.
