Arroyo Grande weather in December

In December, Arroyo Grande sees average daytime highs of 59°F and overnight lows near 47°F, with 2.8 in of rain across 6.1 wet days and about 9.7 hours of daylight. It is the 10th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 59°F through the month. The sky is clear or mostly clear about 48% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 48 min at the start of December to 9 h 42 min by month's end. Set against the rest of the year, December is Arroyo Grande's 9th-clearest and 6th-windiest month. For the whole year in context, see Arroyo Grande's year-round climate.

Daytime high
59°
10th warmest
Overnight low
47°
2nd coldest
Rainfall
2.8 in
6.1 wet days
Daylight
9 h 36 min
7:09 AM – 4:48 PM
Cloud cover
44%
9th clearest
Wind
7 mph
6th windiest
Solar energy
2.84 kWh/m²
Travel score
5.2
out of 10

Arroyo Grande is city in San Luis Obispo County, California, United States.

Density
1,199/km²
people per km²
Founded
1862

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 59°F through the month.

A typical December day in Arroyo Grande reaches about 59°F in the afternoon and slips back to 47°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 54°F and 65°F. Set against its neighbours, December runs about 4°F cooler than November and on par with January.

40°50°60°70°151015202531
Avg high (°F)Avg low (°F)
16149
26049
36048
46048
56048
66048
76048
86048
96048
105948
115947
125947
135947
145947
155947
165947
175947
185947
195947
205947
215947
225947
235947
245947
255947
265947
275947
285947
295947
305947
315947

Arroyo Grande weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan59° / 47°3.87.29.95.1
Feb59° / 48°3.67.810.74.9
Mar60° / 49°2.86.311.75.5
Apr62° / 50°1.03.312.96.4
May64° / 53°0.41.613.87.3
Jun66° / 56°0.10.414.38.2
Jul69° / 59°0.00.214.18.5
Aug70° / 59°0.00.113.38.8
Sep70° / 59°0.00.412.28.7
Oct68° / 56°0.81.811.18.3
Nov64° / 51°1.43.710.26.9
Dec59° / 47°2.86.19.75.2

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 48% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 14% of December, with mostly cloudy or overcast conditions the remaining 38%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16733
26634
36634
46535
56436
66436
76337
86337
96337
106238
116238
126238
136238
146238
156238
166238
176238
186337
196337
206337
216337
226238
236238
246238
256139
266139
276040
285941
295941
305842
315842

Chance of precipitation in December

Any precipitation

Arroyo Grande gets around 2.8 in of rain over 6.1 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 20% and peaks near 24% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
116
217
317
418
518
618
719
819
919
1019
1120
1220
1320
1420
1520
1620
1720
1820
1920
2021
2121
2221
2321
2421
2522
2622
2722
2823
2923
3023
3124

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 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1982
2982
3982
4982
5982
6982
7982
8982
9982
10982
11982
12982
13991
14991
15991
16991
17991
18991
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
29991
30991
31991

Wind in December

Winds average 7 mph in December.

Across December, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227light breeze
237light breeze
247light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 48 min at the start of December to 9 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 6:58 AM to 7:16 AM, and sunset from 4:46 PM to 4:55 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.86:584:46
29.86:594:46
39.87:004:46
49.87:004:46
59.77:014:46
69.77:024:46
79.77:034:46
89.77:044:46
99.77:044:46
109.77:054:47
119.77:064:47
129.77:074:47
139.77:074:47
149.77:084:47
159.77:084:48
169.67:094:48
179.67:104:48
189.67:104:49
199.67:114:49
209.67:114:49
219.67:124:50
229.67:124:50
239.67:134:51
249.67:134:51
259.67:144:52
269.67:144:52
279.67:144:53
289.67:154:54
299.77:154:54
309.77:154:55
319.77:164:55

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.84 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.84 kWh/m² to a high of 8.24 kWh/m² in June across the year — December's 2.84 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
13.0Moderate
22.9Moderate
32.9Moderate
42.9Moderate
52.9Moderate
62.9Moderate
72.8Moderate
82.8Moderate
92.8Moderate
102.8Moderate
112.8Moderate
122.8Moderate
132.8Moderate
142.8Moderate
152.8Moderate
162.8Moderate
172.8Moderate
182.8Moderate
192.8Moderate
202.8Moderate
212.8Moderate
222.8Moderate
232.8Moderate
242.8Moderate
252.8Moderate
262.8Moderate
272.9Moderate
282.9Moderate
292.9Moderate
302.9Moderate
312.9Moderate
Planning a trip in December

Is December a good time to visit Arroyo Grande?

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

5.2
Sightseeing
10th-best month of the year
0.2
Beach & pool
10th-best month of the year

December is a reasonable time to visit Arroyo Grande for sightseeing.

What to pack for Arroyo Grande in December

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

In December, Arroyo Grande sees daytime highs around 59°F and nights near 47°F. Worth packing: a warm layer. About 6 days see rain.

a warm layer

Sea temperature near Arroyo Grande in December

The nearest coast averages about 57°F in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in September at about 60°F and coldest in April near 54°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

52°54°56°58°60°62°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°F)Comfort
Jan56Bracing
Feb56Bracing
Mar55Bracing
Apr54Bracing
May54Bracing
Jun55Bracing
Jul58Bracing
Aug59Cool
Sep60Cool
Oct60Cool
Nov58Bracing
Dec57Bracing

UV index in Arroyo Grande in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 3. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Arroyo Grande peaks around June 21 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 21UV 11Dec 15UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7Very high
May8Very high
Jun11Extreme
Jul10Extreme
Aug10Extreme
Sep8Very high
Oct6High
Nov3Moderate
Dec3Moderate

Air quality in Arroyo Grande 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 Arroyo Grande is worst in August — around 19 µg/m³ PM2.5 (moderate), about 4.5× the cleanest month (June, 4 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodAug 2218 µg/m³Jun 124 µg/m³
PM2.5 (µg/m³)Level
Jan7Good
Feb6Good
Mar7Good
Apr6Good
May5Good
Jun4Good
Jul7Good
Aug19Moderate
Sep17Moderate
Oct7Good
Nov6Good
Dec5Good
Location & terrain

Where is Arroyo Grande?

Arroyo Grande sits at 35.1°N, 120.6°W, 118 ft above sea level, in United States. The nearest listed city is Nipomo, 8.1 mi away.

Topography around Arroyo Grande

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

Within 2 miles, the terrain around Arroyo Grande has only modest variations in elevation — a maximum elevation change of 486 ft around an average of 151 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,808 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 5,715 ft.

The land around Arroyo Grande is covered by artificial surfaces (48%) and grassland (21%) within 2 miles, grassland (32%), water (25%) and trees (23%) within 10 miles, and grassland (47%) and water (27%) within 50 miles.

2 miles
486 ft
10 miles
2,808 ft
50 miles
5,715 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Nipomo 8.1 mi · San Luis Obispo 12 mi · Santa Maria 14 mi · Orcutt 19 mi · Atascadero 26 mi · Lompoc 34 mi · Paso Robles 35 mi · Isla Vista 64 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 Arroyo Grande (35.1186°, -120.5907°, elevation 118 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).