Atascadero weather in September

In September, Atascadero sees average daytime highs of 78°F and overnight lows near 57°F, with 0.1 in of rain across 0.4 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 79°F in the first days to 77°F by the end. The sky is clear or mostly clear about 90% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Atascadero's 2nd-clearest and 11th-windiest month. For the whole year in context, see Atascadero's year-round climate.

Daytime high
78°
3rd warmest
Overnight low
57°
10th coldest
Rainfall
0.1 in
0.4 wet days
Daylight
12 h 12 min
5:50 AM – 6:04 PM
Cloud cover
13%
2nd clearest
Wind
4 mph
11th windiest
Solar energy
6.21 kWh/m²
Travel score
9.2
out of 10

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

Density
441/km²
people per km²
Founded
1979

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 79°F in the first days to 77°F by the end.

A typical September day in Atascadero reaches about 78°F in the afternoon and slips back to 57°F overnight — a 21°F spread between the day's warmth and the night's chill. On most days the high lands between 70°F and 86°F. Set against its neighbours, September runs about 2°F cooler than August and about 5°F warmer than October.

50°60°70°80°90°151015202530
Avg high (°F)Avg low (°F)
18059
28059
37959
47959
57959
67958
77958
87958
97858
107858
117858
127858
137858
147858
157857
167857
177857
187857
197757
207757
217757
227757
237757
247757
257756
267756
277756
287756
297656
307656

Atascadero weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan59° / 43°3.37.19.95.0
Feb60° / 44°3.37.710.75.2
Mar63° / 46°2.56.411.76.3
Apr67° / 48°0.93.512.97.5
May71° / 51°0.41.713.88.5
Jun76° / 55°0.10.414.49.4
Jul79° / 59°0.00.114.29.2
Aug80° / 59°0.00.213.39.1
Sep78° / 57°0.10.412.29.2
Oct73° / 53°0.7211.18.8
Nov65° / 47°1.13.610.17.1
Dec59° / 42°2.56.29.65.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 90% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 4% of September, with mostly cloudy or overcast conditions the remaining 6%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1973
2973
3973
4964
5964
6964
7964
8964
9964
10964
11964
12955
13955
14955
15955
16955
17946
18937
19937
20937
21937
22937
23937
24937
25937
26937
27928
28928
29928
30928

Chance of precipitation in September

Any precipitation

Atascadero gets around 0.1 in of rain over 0.4 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 2% and peaks near 3% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
41
51
61
71
81
91
101
111
121
131
141
151
161
171
181
191
202
212
222
232
242
252
262
273
283
293
303

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 53% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
14049101
24148101
3434791
4444691
5454681
6464581
7474571
8484471
9494461
10504451
11514351
12524341
13534340
14534340
15534340
16544330
17554230
18554230
19554230
20564130
21564130
22574030
23574030
24574030
25583930
26603820
27603820
28613720
29633520
30643420

Wind in September

Winds average 4 mph in September.

Across September, daily wind ranges from about 4 mph on the calmest days to 4 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 48 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over September. Sunrise moves from 5:39 AM to 6:01 AM, and sunset from 6:26 PM to 5:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:396:26
212.75:406:25
312.75:406:23
412.75:416:22
512.65:426:20
612.65:436:19
712.65:436:17
812.55:446:16
912.55:456:14
1012.45:466:13
1112.45:476:11
1212.45:476:10
1312.35:486:08
1412.35:496:07
1512.35:506:05
1612.25:506:04
1712.25:516:02
1812.15:526:01
1912.15:535:59
2012.15:545:58
2112.05:545:56
2212.05:555:54
2312.05:565:53
2411.95:575:51
2511.95:575:50
2611.85:585:48
2711.85:595:47
2811.86:005:45
2911.76:015:44
3011.76:015:43

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.21 kWh/m².

For context, solar energy here swings from a low near 2.72 kWh/m² to a high of 8.26 kWh/m² in June across the year — September's 6.21 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.8Intense
26.8Intense
36.8Intense
46.7Intense
56.7Intense
66.6Intense
76.6Intense
86.5Intense
96.5Intense
106.5Intense
116.4Intense
126.4Intense
136.3Intense
146.3Intense
156.2Intense
166.2Intense
176.2Intense
186.1Intense
196.0Intense
206.0Intense
216.0Bright
225.9Bright
235.9Bright
245.8Bright
255.8Bright
265.7Bright
275.7Bright
285.6Bright
295.6Bright
305.5Bright
Planning a trip in September

Is September a good time to visit Atascadero?

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

9.2
Sightseeing
2nd-best month of the year
8.5
Beach & pool
3rd-best month of the year

September is one of the better times to visit Atascadero for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Atascadero in September

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

In September, Atascadero sees daytime highs around 78°F and nights near 57°F. Pack sun protection. Worth having: light clothes.

sun protectionlight clothes

Sea temperature near Atascadero in September

The nearest coast averages about 60°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 14 mi away) 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
Jun56Bracing
Jul58Bracing
Aug59Cool
Sep60Cool
Oct60Cool
Nov58Bracing
Dec57Bracing

UV index in Atascadero in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Atascadero peaks around June 21 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 21UV 11Dec 14UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May8Very high
Jun11Extreme
Jul10Extreme
Aug10Extreme
Sep7Very high
Oct6High
Nov3Moderate
Dec3Moderate

Air quality in Atascadero in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Atascadero 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 Atascadero?

Atascadero sits at 35.5°N, 120.7°W, 879 ft above sea level, in United States. The nearest listed city is Paso Robles, 9.3 mi away.

Topography around Atascadero

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

Within 2 miles, the terrain around Atascadero has only modest variations in elevation — a maximum elevation change of 600 ft around an average of 948 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,549 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,698 ft.

The land around Atascadero is covered by trees (39%), grassland (35%) and artificial surfaces (23%) within 2 miles, grassland (56%) and trees (33%) within 10 miles, and grassland (54%) and water (22%) within 50 miles.

2 miles
600 ft
10 miles
2,549 ft
50 miles
4,698 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Paso Robles 9.3 mi · San Luis Obispo 14 mi · Arroyo Grande 26 mi · Nipomo 33 mi · Santa Maria 39 mi · Orcutt 45 mi · Coalinga 48 mi · Lompoc 60 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 Atascadero (35.4894°, -120.6707°, elevation 879 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).