Longmont weather in December: Longmont, Colorado: normal highs, lows, rain and records for December
Longmont in December has a normal high of 45°F and a normal low of 15°F, a daily mean of 30°F, falling from 47°F on the 1st to 44°F by the 31st. Measurable precipitation falls on 3 days in a normal December, 0.46 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 7°C and low of −10°C, 12 mm of precipitation in December.
- NOAA stationLongmont (2 mi ESE)
- Station IDUSC00055116
- Location40.17°N 105.08°W
- Elevation4,950 ft (1,509 m)
- From the center1 miles
- Population99,818
- Jan 45° 14°
- Feb 47° 17°
- Mar 57° 26°
- Apr 63° 32°
- May 73° 41°
- Jun 84° 51°
- Jul 91° 55°
- Aug 88° 54°
- Sep 80° 46°
- Oct 66° 33°
- Nov 54° 24°
- Dec 45° 15°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Longmont in December?
The normal high is 45°F and the normal low 15°F, for a daily mean of 29.6°F. December is 8.9°F cooler than November and 0.2°F warmer than January. December is the 11th warmest month of the year in Longmont and the 12th wettest. Across the month the normal high falls 3°F, from 47°F on December 1 to 44°F on December 31. From one year to the next December's mean temperature typically moves about 3.6°F either way (NOAA's standard deviation), so roughly two Decembers in three average between 26°F and 33°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 12%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| December 1 | 47°F | 18°F | 12% | 6% |
| December 8 | 46°F | 16°F | 11% | 5% |
| December 15 | 44°F | 14°F | 10% | 4% |
| December 22 | 44°F | 13°F | 10% | 4% |
| December 31 | 44°F | 13°F | 10% | 4% |
Every day of December: normal high, low and chance of precipitation (warmest afternoon December 1, coldest night December 23)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| December 1 | 47°F | 18°F | 12% | 6% | 9 h 30 min |
| December 2 | 47°F | 18°F | 12% | 6% | 9 h 30 min |
| December 3 | 47°F | 17°F | 12% | 6% | 9 h 30 min |
| December 4 | 47°F | 17°F | 12% | 6% | 9 h 30 min |
| December 5 | 46°F | 17°F | 12% | 5% | 9 h 30 min |
| December 6 | 46°F | 16°F | 11% | 5% | 9 h 30 min |
| December 7 | 46°F | 16°F | 11% | 5% | 9 h 30 min |
| December 8 | 46°F | 16°F | 11% | 5% | 9 h 30 min |
| December 9 | 45°F | 15°F | 11% | 5% | 9 h 20 min |
| December 10 | 45°F | 15°F | 11% | 5% | 9 h 20 min |
| December 11 | 45°F | 15°F | 11% | 4% | 9 h 20 min |
| December 12 | 45°F | 15°F | 11% | 4% | 9 h 20 min |
| December 13 | 45°F | 14°F | 11% | 4% | 9 h 20 min |
| December 14 | 44°F | 14°F | 11% | 4% | 9 h 20 min |
| December 15 | 44°F | 14°F | 10% | 4% | 9 h 20 min |
| December 16 | 44°F | 14°F | 10% | 4% | 9 h 20 min |
| December 17 | 44°F | 14°F | 10% | 4% | 9 h 20 min |
| December 18 | 44°F | 14°F | 10% | 4% | 9 h 20 min |
| December 19 | 44°F | 14°F | 10% | 4% | 9 h 20 min |
| December 20 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 21 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 22 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 23 | 44°F | 13°F | 10% | 3% | 9 h 20 min |
| December 24 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 25 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 26 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 27 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 28 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 29 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 30 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
| December 31 | 44°F | 13°F | 10% | 4% | 9 h 20 min |
- Normal high
- 45°FDecember average
- Normal low
- 15°FDecember average
- Precipitation
- 0.46 inmonth total
- Days with precipitation
- 30.01 inch or more
- Nights at 32°F or colder
- 31
- Daylight
- 9 h 30 min to 9 h 20 minDecember 1 to December 31
- Sunshine
- 76%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USC00055116; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Longmont in December?
On a given December day the chance of 0.01 inch or more is 10% on average, highest around December 1 (12%). In all, 0.46 in falls on 3 days of a normal December.
In a normal December in Longmont, 31 nights fall to freezing and 3 days stay below freezing all day.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USC00055116.
What are the records for December in Longmont?
The warmest December temperature on this station's record (since 1893) is 78°F, on December 11, 1939; the coldest is −32°F, on December 23, 1924. The wettest December brought 4.23 in (1913); the snowiest, 32.0 inches (1982).
The December mean against the 1991-2020 normal of 29.6°F: 2021 38.1°F (+8.5), 2022 29.1°F (−0.5), 2023 36.5°F (+6.9), 2024 37.9°F (+8.3), 2025 40.0°F (+10.4). 4 of 5 ran warmer than normal.
| December | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 38.1°F | +8.5°F | 0.02 in |
| 2022 | 29.1°F | −0.5°F | 1.61 in |
| 2023 | 36.5°F | +6.9°F | 0.25 in |
| 2024 | 37.9°F | +8.3°F | 0.04 in |
| 2025 | 40.0°F | +10.4°F | 0.58 in |
Source: records: ACIS, station USC00055116; recent months: ACIS, station USC00055116. Records and recent months use complete months only.
How does December in Longmont compare across Colorado?
Across the 125 places PlainClimate covers in Colorado, December normal highs run from 27°F in Crested Butte to 49°F in Campo; Longmont's is 45°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.