Hillsboro weather in December: Hillsboro, Oregon: normal highs, lows, rain and records for December
Hillsboro in December has a normal high of 46°F and a normal low of 33°F, a daily mean of 40°F, falling from 48°F on the 1st to 46°F by the 31st. Measurable precipitation falls on 20 days in a normal December, 6.05 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 8°C and low of 1°C, 154 mm of precipitation in December.
- NOAA stationPortland-Hillsboro Airport
- Station IDUSW00094261
- Location45.54°N 122.95°W
- Elevation204 ft (62 m)
- Population110,337
- Jan 47° 34°
- Feb 51° 34°
- Mar 56° 37°
- Apr 61° 39°
- May 69° 45°
- Jun 74° 49°
- Jul 82° 52°
- Aug 82° 52°
- Sep 76° 48°
- Oct 64° 41°
- Nov 53° 37°
- Dec 46° 33°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Hillsboro in December?
The normal high is 46°F and the normal low 33°F, for a daily mean of 39.8°F. December is 4.8°F cooler than November and 0.6°F cooler than January. December is the 12th warmest month of the year in Hillsboro and the wettest. Across the month the normal high falls 2°F, from 48°F on December 1 to 46°F on December 31. From one year to the next December's mean temperature typically moves about 2.4°F either way (NOAA's standard deviation), so roughly two Decembers in three average between 37°F and 42°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 65%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| December 1 | 48°F | 34°F | 64% | 40% |
| December 8 | 47°F | 34°F | 64% | 41% |
| December 15 | 46°F | 33°F | 65% | 42% |
| December 22 | 46°F | 33°F | 65% | 42% |
| December 31 | 46°F | 33°F | 65% | 41% |
Every day of December: normal high, low and chance of precipitation (warmest afternoon December 1, coldest night December 18)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| December 1 | 48°F | 34°F | 64% | 40% | 9 h |
| December 2 | 48°F | 34°F | 64% | 40% | 9 h |
| December 3 | 48°F | 34°F | 64% | 40% | 9 h |
| December 4 | 48°F | 34°F | 64% | 40% | 9 h |
| December 5 | 47°F | 34°F | 64% | 41% | 8 h 50 min |
| December 6 | 47°F | 34°F | 64% | 41% | 8 h 50 min |
| December 7 | 47°F | 34°F | 64% | 41% | 8 h 50 min |
| December 8 | 47°F | 34°F | 64% | 41% | 8 h 50 min |
| December 9 | 47°F | 34°F | 64% | 41% | 8 h 50 min |
| December 10 | 46°F | 33°F | 64% | 41% | 8 h 50 min |
| December 11 | 46°F | 33°F | 64% | 41% | 8 h 50 min |
| December 12 | 46°F | 33°F | 64% | 41% | 8 h 50 min |
| December 13 | 46°F | 33°F | 64% | 41% | 8 h 50 min |
| December 14 | 46°F | 33°F | 64% | 42% | 8 h 40 min |
| December 15 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 16 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 17 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 18 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 19 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 20 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 21 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 22 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 23 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 24 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 25 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 26 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 27 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 28 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 29 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 30 | 46°F | 33°F | 65% | 42% | 8 h 40 min |
| December 31 | 46°F | 33°F | 65% | 41% | 8 h 40 min |
- Normal high
- 46°FDecember average
- Normal low
- 33°FDecember average
- Precipitation
- 6.05 inmonth total
- Days with precipitation
- 200.01 inch or more
- Nights at 32°F or colder
- 14
- Daylight
- 9 h to 8 h 40 minDecember 1 to December 31
- Sunshine
- 52%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094261; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Hillsboro in December?
On a given December day the chance of 0.01 inch or more is 64% on average, highest around December 23 (65%). In all, 6.05 in falls on 20 days of a normal December, 1 of them with an inch or more.
In a normal December in Hillsboro, 14 nights fall to freezing and 1 days stay below freezing all day.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094261.
How humid and windy is Hillsboro in December?
At 3 p.m. the normal temperature is 44°F with 77% relative humidity and a dew point of 37°F; at 6 a.m. it is 36°F with 91% humidity. The wind averages 4.8 mph, most often from the south-southeast in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 36°F | 34°F | 91% | 4.1 mph | – |
| 9 a.m. | 37°F | 34°F | 89% | 4.4 mph | – |
| noon | 42°F | 37°F | 81% | 5.6 mph | – |
| 3 p.m. | 44°F | 37°F | 77% | 6.1 mph | – |
| 6 p.m. | 40°F | 36°F | 85% | 5.1 mph | – |
| 9 p.m. | 39°F | 35°F | 88% | 4.7 mph | – |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094261. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for December in Hillsboro?
The warmest December temperature on Hillsboro's official record (since 1929) is 64°F, on December 10, 1933; the coldest is −2°F, on December 8, 1972. The wettest December brought 14.83 in (1996); the snowiest, 13.1 inches (1968).
The December mean against the 1991-2020 normal of 39.8°F: 2021 38.3°F (−1.5), 2022 38.1°F (−1.7), 2023 43.9°F (+4.1), 2024 42.7°F (+2.9), 2025 45.5°F (+5.7). 3 of 5 ran warmer than normal.
| December | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 38.3°F | −1.5°F | 6.82 in |
| 2022 | 38.1°F | −1.7°F | 7.45 in |
| 2023 | 43.9°F | +4.1°F | 7.68 in |
| 2024 | 42.7°F | +2.9°F | 6.29 in |
| 2025 | 45.5°F | +5.7°F | 7.05 in |
Source: records: ACIS, NWS threaded record HIOthr; recent months: ACIS, station USW00094261. Records and recent months use complete months only.
How does December in Hillsboro compare across Oregon?
Across the 105 places PlainClimate covers in Oregon, December normal highs run from 33°F in Halfway to 55°F in Bandon; Hillsboro's is 46°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.