Romeoville weather in December: Romeoville, Illinois: normal highs, lows, rain and records for December
Romeoville in December has a normal high of 37°F and a normal low of 22°F, a daily mean of 29°F, falling from 42°F on the 1st to 33°F by the 31st. Measurable precipitation falls on 11 days in a normal December, 2.15 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 3°C and low of −6°C, 55 mm of precipitation and 19 cm of snow in December.
- NOAA stationRomeoville Weather Office
- Station IDUSC00117457
- Location41.60°N 88.08°W
- Elevation660 ft (201 m)
- From the center2 miles
- Population41,177
- Jan 32° 16°
- Feb 36° 20°
- Mar 49° 30°
- Apr 61° 40°
- May 72° 50°
- Jun 82° 60°
- Jul 85° 65°
- Aug 83° 63°
- Sep 76° 55°
- Oct 64° 44°
- Nov 49° 32°
- Dec 37° 22°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Romeoville in December?
The normal high is 37°F and the normal low 22°F, for a daily mean of 29.4°F. December is 11.0°F cooler than November and 5.5°F warmer than January. December is the 10th warmest month of the year in Romeoville and the 11th wettest. Across the month the normal high falls 9°F, from 42°F on December 1 to 33°F on December 31. From one year to the next December's mean temperature typically moves about 5.1°F either way (NOAA's standard deviation), so roughly two Decembers in three average between 24°F and 35°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 35%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| December 1 | 42°F | 26°F | 32% | 18% |
| December 8 | 39°F | 24°F | 33% | 18% |
| December 15 | 37°F | 22°F | 34% | 18% |
| December 22 | 35°F | 20°F | 34% | 18% |
| December 31 | 33°F | 18°F | 35% | 18% |
Every day of December: normal high, low and chance of precipitation (warmest afternoon December 1, coldest night December 31)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| December 1 | 42°F | 26°F | 32% | 18% | 9 h 20 min |
| December 2 | 41°F | 26°F | 32% | 18% | 9 h 20 min |
| December 3 | 41°F | 26°F | 32% | 18% | 9 h 20 min |
| December 4 | 41°F | 25°F | 33% | 18% | 9 h 20 min |
| December 5 | 40°F | 25°F | 33% | 18% | 9 h 20 min |
| December 6 | 40°F | 25°F | 33% | 18% | 9 h 20 min |
| December 7 | 39°F | 24°F | 33% | 18% | 9 h 20 min |
| December 8 | 39°F | 24°F | 33% | 18% | 9 h 20 min |
| December 9 | 39°F | 24°F | 33% | 18% | 9 h 20 min |
| December 10 | 38°F | 24°F | 33% | 18% | 9 h 10 min |
| December 11 | 38°F | 23°F | 33% | 18% | 9 h 10 min |
| December 12 | 38°F | 23°F | 33% | 18% | 9 h 10 min |
| December 13 | 37°F | 23°F | 34% | 18% | 9 h 10 min |
| December 14 | 37°F | 22°F | 34% | 18% | 9 h 10 min |
| December 15 | 37°F | 22°F | 34% | 18% | 9 h 10 min |
| December 16 | 37°F | 22°F | 34% | 18% | 9 h 10 min |
| December 17 | 36°F | 22°F | 34% | 18% | 9 h 10 min |
| December 18 | 36°F | 21°F | 34% | 18% | 9 h 10 min |
| December 19 | 36°F | 21°F | 34% | 18% | 9 h 10 min |
| December 20 | 35°F | 21°F | 34% | 18% | 9 h 10 min |
| December 21 | 35°F | 21°F | 34% | 18% | 9 h 10 min |
| December 22 | 35°F | 20°F | 34% | 18% | 9 h 10 min |
| December 23 | 35°F | 20°F | 34% | 18% | 9 h 10 min |
| December 24 | 34°F | 20°F | 34% | 18% | 9 h 10 min |
| December 25 | 34°F | 20°F | 34% | 18% | 9 h 10 min |
| December 26 | 34°F | 19°F | 34% | 18% | 9 h 10 min |
| December 27 | 34°F | 19°F | 35% | 18% | 9 h 10 min |
| December 28 | 34°F | 19°F | 35% | 18% | 9 h 10 min |
| December 29 | 33°F | 19°F | 35% | 18% | 9 h 10 min |
| December 30 | 33°F | 18°F | 35% | 18% | 9 h 10 min |
| December 31 | 33°F | 18°F | 35% | 18% | 9 h 10 min |
- Normal high
- 37°FDecember average
- Normal low
- 22°FDecember average
- Precipitation
- 2.15 inmonth total
- Days with precipitation
- 110.01 inch or more
- Snowfall
- 7.5 inmonth total
- Nights at 32°F or colder
- 27
- Daylight
- 9 h 20 min to 9 h 10 minDecember 1 to December 31
- Sunshine
- 61%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USC00117457; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain or snow in Romeoville in December?
On a given December day the chance of 0.01 inch or more is 34% on average, highest around December 30 (35%). In all, 2.15 in falls on 11 days of a normal December.
In a normal December in Romeoville, 27 nights fall to freezing, 11 days stay below freezing all day and snowfall averages 7.5 inches.
Snow falls on 6 days in a normal December, and an inch or more covers the ground on 9 days.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USC00117457.
What are the records for December in Romeoville?
The warmest December temperature on this station's record (since 1992) is 71°F, on December 3, 2012; the coldest is −12°F, on December 19, 2016. The wettest December brought 5.85 in (2015); the snowiest, 30.0 inches (2000).
The December mean against the 1991-2020 normal of 29.4°F: 2021 36.8°F (+7.4), 2022 27.9°F (−1.5), 2023 37.6°F (+8.2), 2024 30.9°F (+1.6), 2025 25.3°F (−4.1). 3 of 5 ran warmer than normal.
| December | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 36.8°F | +7.4°F | 2.27 in |
| 2022 | 27.9°F | −1.5°F | 2.74 in |
| 2023 | 37.6°F | +8.2°F | 3.30 in |
| 2024 | 30.9°F | +1.6°F | 1.80 in |
| 2025 | 25.3°F | −4.1°F | 2.30 in |
Source: records: ACIS, station USC00117457; recent months: ACIS, station USC00117457. Records and recent months use complete months only.
How does December in Romeoville compare across Illinois?
Across the 144 places PlainClimate covers in Illinois, December normal highs run from 33°F in Galena to 48°F in Anna; Romeoville's is 37°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.