Half Moon Bay weather in December: Half Moon Bay, California: normal highs, lows, rain and records for December
Half Moon Bay in December has a normal high of 59°F and a normal low of 43°F, a daily mean of 51°F, holding near 59°F all month. Measurable precipitation falls on 13 days in a normal December, 5.17 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 15°C and low of 6°C, 131 mm of precipitation in December.
- NOAA stationHalf Moon Bay
- Station IDUSC00043714
- Location37.47°N 122.44°W
- Elevation27 ft (8 m)
- Population11,324
- Jan 59° 43°
- Feb 60° 43°
- Mar 60° 44°
- Apr 61° 45°
- May 62° 48°
- Jun 64° 50°
- Jul 65° 53°
- Aug 66° 54°
- Sep 66° 51°
- Oct 66° 48°
- Nov 63° 45°
- Dec 59° 43°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Half Moon Bay in December?
The normal high is 59°F and the normal low 43°F, for a daily mean of 50.9°F. December is 2.8°F cooler than November and 0.5°F cooler than January. December is the 12th warmest month of the year in Half Moon Bay and the wettest. Across the month the normal high falls 1°F, from 60°F on December 1 to 59°F on December 31. From one year to the next December's mean temperature typically moves about 1.9°F either way (NOAA's standard deviation), so roughly two Decembers in three average between 49°F and 53°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 45%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| December 1 | 60°F | 43°F | 41% | 23% |
| December 8 | 59°F | 43°F | 42% | 24% |
| December 15 | 59°F | 43°F | 43% | 26% |
| December 22 | 59°F | 43°F | 43% | 26% |
| December 31 | 59°F | 43°F | 45% | 26% |
Every day of December: normal high, low and chance of precipitation (warmest afternoon December 1, coldest night December 13)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| December 1 | 60°F | 43°F | 41% | 23% | 9 h 50 min |
| December 2 | 60°F | 43°F | 42% | 23% | 9 h 50 min |
| December 3 | 60°F | 43°F | 42% | 23% | 9 h 50 min |
| December 4 | 60°F | 43°F | 42% | 23% | 9 h 40 min |
| December 5 | 60°F | 43°F | 42% | 24% | 9 h 40 min |
| December 6 | 59°F | 43°F | 42% | 24% | 9 h 40 min |
| December 7 | 59°F | 43°F | 42% | 24% | 9 h 40 min |
| December 8 | 59°F | 43°F | 42% | 24% | 9 h 40 min |
| December 9 | 59°F | 43°F | 42% | 25% | 9 h 40 min |
| December 10 | 59°F | 43°F | 43% | 25% | 9 h 40 min |
| December 11 | 59°F | 43°F | 43% | 25% | 9 h 40 min |
| December 12 | 59°F | 43°F | 43% | 25% | 9 h 40 min |
| December 13 | 59°F | 43°F | 43% | 25% | 9 h 40 min |
| December 14 | 59°F | 43°F | 43% | 26% | 9 h 40 min |
| December 15 | 59°F | 43°F | 43% | 26% | 9 h 40 min |
| December 16 | 59°F | 43°F | 43% | 26% | 9 h 40 min |
| December 17 | 59°F | 43°F | 43% | 26% | 9 h 40 min |
| December 18 | 59°F | 43°F | 43% | 26% | 9 h 40 min |
| December 19 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 20 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 21 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 22 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 23 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 24 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 25 | 59°F | 43°F | 43% | 26% | 9 h 30 min |
| December 26 | 59°F | 43°F | 44% | 26% | 9 h 30 min |
| December 27 | 59°F | 43°F | 44% | 26% | 9 h 40 min |
| December 28 | 59°F | 43°F | 44% | 26% | 9 h 40 min |
| December 29 | 59°F | 43°F | 44% | 26% | 9 h 40 min |
| December 30 | 59°F | 43°F | 44% | 26% | 9 h 40 min |
| December 31 | 59°F | 43°F | 45% | 26% | 9 h 40 min |
- Normal high
- 59°FDecember average
- Normal low
- 43°FDecember average
- Precipitation
- 5.17 inmonth total
- Days with precipitation
- 130.01 inch or more
- Nights at 32°F or colder
- 1
- Daylight
- 9 h 50 min to 9 h 40 minDecember 1 to December 31
- Days at 70°F or more
- 1
- Sunshine
- 74%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USC00043714; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Half Moon Bay in December?
On a given December day the chance of 0.01 inch or more is 43% on average, highest around December 31 (45%). In all, 5.17 in falls on 13 days of a normal December, 1 of them with an inch or more.
In a normal December in Half Moon Bay, 1 nights fall to freezing.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USC00043714.
What are the records for December in Half Moon Bay?
The warmest December temperature on this station's record (since 1939) is 79°F, on December 4, 1958; the coldest is 19°F, on December 23, 1990. The wettest December brought 13.81 in (1955).
The December mean against the 1991-2020 normal of 50.9°F: 2021 50.4°F (−0.5), 2022 49.8°F (−1.1), 2023 53.5°F (+2.6), 2024 53.4°F (+2.5), 2025 55.6°F (+4.7). 3 of 5 ran warmer than normal.
| December | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 50.4°F | −0.5°F | 11.31 in |
| 2022 | 49.8°F | −1.1°F | 10.54 in |
| 2023 | 53.5°F | +2.6°F | 4.91 in |
| 2024 | 53.4°F | +2.5°F | 4.74 in |
| 2025 | 55.6°F | +4.7°F | 3.58 in |
Source: records: ACIS, station USC00043714; recent months: ACIS, station USC00043714. Records and recent months use complete months only.
How does December in Half Moon Bay compare across California?
Across the 219 places PlainClimate covers in California, December normal highs run from 38°F in Tahoma to 71°F in Anaheim; Half Moon Bay's is 59°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Half Moon Bay in November63°F by day, 45°F at night
- Half Moon Bay in January59°F by day, 43°F at night
- Half Moon Bay through the yearEvery month, frost dates, records and recent years
- California in DecemberThe statewide normal and the warmest and coolest places
- Anaheim: California's warmest Decembernormal high 71°F