Thornton (CO) Temperature by Month
The average annual maximum temperature in Thornton, Colorado, United States of America is 19°C (66°F), with daytime highs ranging from 7°C (45°F) in December to 32°C (90°F) in July. This page covers monthly averages, day-night differences, and how Thornton compares to cities worldwide.
Thornton Monthly Temperatures
In Thornton, temperatures can shift dramatically between very warm in summer and cold in winter. Nights follow the same pattern, with lows ranging from 15°C (59°F) in July to -8°C (18°F) in December.
The chart below illustrates the average maximum day and minimum night temperatures in Thornton by month:
Low temperatures are most often recorded between 4 AM and 6 AM, while highs typically occur around 3 PM. July, the city's warmest month, sees 323 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Thornton 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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Thornton vs World: Temperature Compared
Thornton'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:
Athens, Greece sits at 23°C (73°F) on average, with hot dry summers and mild winters characteristic of the Mediterranean.
Interlaken, Switzerland averages 8°C (46°F) a year, with cold winters and cool summers thanks to its Alpine setting.
Beijing, China averages 20°C (68°F) annually, but with big seasonal swings — very cold winters and hot summers.
Perth, Australia averages 25°C (77°F) annually, with a classic Mediterranean climate — hot dry summers and mild wet winters.
What Does the Temperature Feel Like in Thornton?
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 Thornton, December is the coolest month, with average highs of 7°C (45°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.
For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained — so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.
For more on Thornton's weather — including monthly rainfall, sunshine hours, and humidity — visit our Thornton climate page.
