Thornton, CO weather in December
December in Thornton: chilly and mostly dry, with some snow. Highs 46°F, lows 18°F, about 4 days with rain or snow and about 6.6 in of snow. This is the depth of winter in Thornton.
- Normal high
- 46°F
- Normal low
- 18°F
- Wet days
- 4
- 0.5 in total
- Snowfall
- 6.6 in
- snow on the ground 10 days
How December changes from start to finish
| December 1 | December 31 | |
|---|---|---|
| Normal high | 49°F | 46°F |
| Normal low | 20°F | 17°F |
| Chance of a wet day | 13% | 12% |
| Sunrise / sunset | 7:02 am / 4:35 pm | 7:21 am / 4:44 pm |
| Daylight | 9.6 h | 9.4 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Mountain Time).
A typical December day
- 6 am26°Fdew point 13°F
- 9 am31°Fdew point 15°F
- Noon40°Fdew point 15°F
- 3 pm41°Fdew point 16°F
- 6 pm32°Fdew point 16°F
- 9 pm28°Fdew point 16°F
NOAA hourly normals (local standard time) from Aurora Buckley Fld ANGB (16 mi away); average wind 8 mph; clear or few clouds in 37% of daytime hours, mostly cloudy or overcast in 46%.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F2 of 31
- Hot dayshigh 90°F or more0 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow4 of 31
- Notable rainat least 0.10 in2 of 31
- Freezing nightslow 32°F or below30 of 31
- Snow on the groundsnow depth 1 in or more10 of 31
Average days per December, counted from daily records for each year 1991-2020.
Rain and snow in December
Normal precipitation is 0.5 in; a dry December brings about 0.2 in and a wet one about 0.5 in (25th and 75th percentiles). Days with half an inch or more are rare. Normal snowfall is 6.6 in, with about 2 days of an inch or more.
How December varies from year to year
- Warmest December, 1991-20201994: average high 50°F
- Coolest December2009: average high 37°F
- Wettest December2006: 2.8 in
- Driest December2002: no measurable precipitation
- Highest reading73°F (December 1, 1998)
- Lowest reading-15°F (December 18, 2016)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
December compared with November and January
| November | December | January | |
|---|---|---|---|
| Normal high | 55°F | 46°F | 47°F |
| Normal low | 26°F | 18°F | 18°F |
| Wet days | 5 | 4 | 4 |
| Comfortable days | 9 | 2 | 2 |
| Daylight | 10.0 h | 9.4 h | 9.7 h |
Highs change by -9°F from November and +1°F into January.
Nearby alternatives in December
- Cooler: Estes Park, CO46 mi · high 40°F · 7 wet days
How Thornton ranks in December
- Normal high223rd warmest of 378 cities; 5th of 17 in Colorado
- Wet days19th driest of 378
- Comfortable days184th most of 340
What to pack for Thornton in December
- A warm jacket – lows near 18°F, highs near 46°F
- Layers – afternoons near 46°F but nights near 18°F
- Waterproof boots – snow on the ground on about 10 days
- A hat and gloves – about 30 freezing nights
Heating and cooling
December has 1029 heating degree days and 0 cooling degree days (base 65°F), 16% of the year's total heating and cooling demand.
Questions
How cold is Thornton in December?
The normal high is 46°F and the normal low is 18°F. From 1991 to 2020 the coldest December reading was -15°F (most recently on December 18, 2016).
Does it rain a lot in Thornton in December?
About 4 days in December have at least 0.01 in of precipitation, and the normal total is 0.5 in. The wettest December in 1991-2020 was in 2006 (2.8 in); the driest was in 2002, with no measurable precipitation.
Does it snow in Thornton in December?
Yes. Normal snowfall in December is 6.6 in, and snow covers the ground on about 10 days.
Is December a good time to visit Thornton?
December ranks 12th of 12 months on our comfort score for Thornton (40 out of 100). It has about 2 comfortable days. The best month is May.
Where the numbers come from
- Temperature, snowfall and snow depth: Denver-Stapleton (USW00023062), 9.1 mi SE of the city center, 5,286 ft (61 ft lower than the city). NOAA normals and daily records, 1991-2020.
- Rain and frost dates: Northglenn (USC00055984), 3.1 mi NW of the city center, 5,407 ft (60 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour and cloud cover: Aurora Buckley Fld ANGB (USW00023036), 16 mi SE of the city center, 5,663 ft (316 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Denver International Airport (725650-03017), 17 mi E of the city center, 5,404 ft (57 ft higher than the city). Hourly observations, 1991-2020.