Hermiston weather in December

In December, Hermiston sees average daytime highs of 42°F and overnight lows near 31°F, with 1.6 in of precipitation across 9.6 wet days and about 8.5 hours of daylight. It is the 12th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 43°F in the first days to 40°F by the end. The sky is clear or mostly clear about 17% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 42 min at the start of December to 8 h 30 min by month's end. Set against the rest of the year, December is Hermiston's 11th-clearest and 11th-windiest month. For the whole year in context, see Hermiston's year-round climate.

Daytime high
42°
12th warmest
Overnight low
31°
1st coldest
Precipitation
1.6 in
9.6 wet days
Daylight
8 h 30 min
7:39 AM – 4:08 PM
Cloud cover
71%
11th clearest
Wind
6 mph
11th windiest
Solar energy
1.29 kWh/m²
Travel score
0.2
out of 10

Hermiston is city in Oregon, USA.

Density
815/km²
people per km²
Founded
1907

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 43°F in the first days to 40°F by the end.

A typical December day in Hermiston reaches about 42°F in the afternoon and slips back to 31°F overnight — a 11°F spread between the day's warmth and the night's chill. On most days the high lands between 29°F and 54°F. Set against its neighbours, December runs about 8°F cooler than November and on par with January.

20°30°40°50°60°151015202531
Avg high (°F)Avg low (°F)
14432
24432
34332
44331
54331
64331
74331
84231
94231
104231
114231
124231
134231
144231
154231
164231
174230
184230
194230
204130
214130
224130
234130
244130
254130
264130
274130
284030
294030
304030
314030

How December really feels in Hermiston

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Hermiston weather by month

How December compares with the rest of the year at a glance. December is the 12th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan42° / 31°1.59.52.28.90.3
Feb48° / 33°1.27.71.510.11.8
Mar56° / 38°1.38.30.311.64.0
Apr65° / 44°1.06.3013.36.2
May74° / 51°0.95.4014.77.6
Jun81° / 57°0.63.3015.57.4
Jul91° / 63°0.11015.24.9
Aug89° / 62°0.21013.95.3
Sep79° / 55°0.32.2012.38.1
Oct65° / 45°1.05.90.110.76.5
Nov50° / 36°1.48.70.79.32.3
Dec42° / 31°1.69.62.68.50.2

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 13% of December, with mostly cloudy or overcast conditions the remaining 70%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13367
23367
33367
43367
53268
63268
73268
83169
93070
103070
113169
123070
133070
142971
152971
162971
172971
182971
192971
202971
212971
222872
232971
242971
252971
262971
272971
283070
292971
302971
312971

Chance of precipitation in December

Any precipitationSnow

Hermiston gets around 1.6 in of rain and snow over 9.6 wet days in December, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 31% and peaks near 31% on the wettest days, and about 3 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1316
2316
3316
4316
5317
6317
7317
8317
9317
10317
11317
12317
13318
14318
15318
16318
17318
18318
19318
20319
21319
22319
23319
243110
253110
263110
273110
283111
293111
303111
313111

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

Most of December feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 6 mph in December.

Across December, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 42 min at the start of December to 8 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:25 AM to 7:45 AM, and sunset from 4:09 PM to 4:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.77:254:09
28.77:264:09
38.77:274:08
48.77:284:08
58.67:294:08
68.67:304:08
78.67:314:07
88.67:324:07
98.67:334:07
108.67:344:07
118.57:354:07
128.57:364:07
138.57:364:07
148.57:374:08
158.57:384:08
168.57:394:08
178.57:394:08
188.57:404:08
198.57:414:09
208.57:414:09
218.57:424:10
228.57:424:10
238.57:434:11
248.57:434:11
258.57:434:12
268.57:444:12
278.57:444:13
288.57:444:14
298.57:454:14
308.57:454:15
318.57:454:16

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.29 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.29 kWh/m² to a high of 7.88 kWh/m² in July across the year — December's 1.29 kWh/m² sits near the bottom.

00.511.52151015202531
Solar energy (kWh/m²)Level
11.4Dim
21.4Dim
31.4Dim
41.4Dim
51.3Dim
61.3Dim
71.3Dim
81.3Dim
91.3Dim
101.3Dim
111.3Dim
121.3Dim
131.3Dim
141.3Dim
151.3Dim
161.3Dim
171.2Dim
181.2Dim
191.3Dim
201.3Dim
211.3Dim
221.3Dim
231.3Dim
241.3Dim
251.3Dim
261.3Dim
271.3Dim
281.3Dim
291.3Dim
301.3Dim
311.3Dim
Planning a trip in December

Is December a good time to visit Hermiston?

Our two travel scores rate December for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

0.2
Sightseeing
12th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Hermiston.

What to pack for Hermiston in December

From December's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In December, Hermiston sees daytime highs around 42°F and nights near 31°F. Pack a warm layer. Worth having: a heavy coat and rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

UV index in Hermiston in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Hermiston peaks around July 16 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 16UV 8Dec 15UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5Moderate
May7Very high
Jun7High
Jul8Very high
Aug6High
Sep5Moderate
Oct4Moderate
Nov1Low
Dec1Low

Air quality in Hermiston in December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December falls, not just the annual average.

Air quality in Hermiston is worst in August — around 25 µg/m³ PM2.5 (moderate), about 3.5× the cleanest month (December, 7 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 1924 µg/m³Dec 217 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar11Good
Apr10Good
May9Good
Jun9Good
Jul15Moderate
Aug25Moderate
Sep20Moderate
Oct11Good
Nov10Good
Dec7Good
Location & terrain

Where is Hermiston?

Hermiston sits at 45.8°N, 119.3°W, 459 ft above sea level, in United States. The nearest listed city is Kennewick, 27 mi away.

Topography around Hermiston

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Hermiston.

Within 2 miles, the terrain around Hermiston has only modest variations in elevation — a maximum elevation change of 236 ft around an average of 509 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 932 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,659 ft.

The land around Hermiston is covered by grassland (45%) and artificial surfaces (29%) within 2 miles, grassland (45%) and cropland (41%) within 10 miles, and grassland (54%) and cropland (35%) within 50 miles.

2 miles
236 ft
10 miles
932 ft
50 miles
5,659 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Kennewick 27 mi · Pendleton 27 mi · Tri-Cities 29 mi · Pasco 29 mi · Richland 31 mi · Sunnyside 48 mi · Walla Walla 48 mi · Yakima 78 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Hermiston (45.8404°, -119.2895°, elevation 459 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).