Agua Caliente weather in September

In September, Agua Caliente sees average daytime highs of 78°F and overnight lows near 55°F, with 0.1 in of rain across 0.5 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 78°F through the month. The sky is clear or mostly clear about 85% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Agua Caliente's 3rd-clearest and 9th-windiest month. For the whole year in context, see Agua Caliente's year-round climate.

Daytime high
78°
3rd warmest
Overnight low
55°
10th coldest
Rainfall
0.1 in
0.5 wet days
Daylight
12 h 12 min
5:57 AM – 6:12 PM
Cloud cover
16%
3rd clearest
Wind
4 mph
9th windiest
Solar energy
5.88 kWh/m²
Travel score
9.1
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 78°F through the month.

A typical September day in Agua Caliente reaches about 78°F in the afternoon and slips back to 55°F overnight — a 23°F spread between the day's warmth and the night's chill. On most days the high lands between 70°F and 87°F. Set against its neighbours, September runs on par with August and about 5°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18056
28056
37956
47956
57956
67956
77956
87956
97956
107956
117855
127855
137855
147855
157855
167855
177855
187855
197855
207855
217855
227855
237855
247855
257855
267754
277754
287754
297754
307754

Agua Caliente 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
Jan57° / 42°4.99.79.64.1
Feb60° / 44°5.18.910.54.8
Mar63° / 46°3.78.511.75.8
Apr66° / 48°1.65.1137.0
May71° / 52°0.83.2148.1
Jun77° / 55°0.2114.69.0
Jul79° / 56°0.00.114.49.2
Aug79° / 56°0.00.213.59.1
Sep78° / 55°0.10.512.39.1
Oct73° / 52°1.12.9118.5
Nov63° / 46°2.569.96.2
Dec57° / 42°4.89.99.44.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 85% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 7% of September, with mostly cloudy or overcast conditions the remaining 8%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1955
2955
3955
4955
5955
6955
7955
8955
9946
10946
11937
12937
13937
14937
15937
16937
17928
18919
19919
20919
21919
22919
239010
248911
258911
268911
278812
288812
298812
308713

Chance of precipitation in September

Any precipitation

Agua Caliente gets around 0.1 in of rain over 0.5 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 5% 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
172
182
192
202
212
222
233
243
253
264
274
284
294
305

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 80% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
172262
273252
374242
475232
576222
677212
777212
878202
979192
1079192
1180182
1280182
1380182
1480182
1580182
1681181
1781181
1881181
1981181
2082171
2182171
2283161
2383161
2483161
2584151
2684151
2785141
2886140
2987130
3087130

Wind in September

Winds average 4 mph in September.

Across September, daily wind ranges from about 4 mph on the calmest days to 5 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
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 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:44 AM to 6:10 AM, and sunset from 6:36 PM to 5:49 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:446:36
212.85:446:34
312.85:456:33
412.75:466:31
512.75:476:29
612.75:486:28
712.65:496:26
812.65:506:25
912.55:516:23
1012.55:526:21
1112.55:526:20
1212.45:536:18
1312.45:546:17
1412.35:556:15
1512.35:566:13
1612.25:576:12
1712.25:586:10
1812.25:596:08
1912.16:006:07
2012.16:016:05
2112.06:016:03
2212.06:026:02
2311.96:036:00
2411.96:045:58
2511.96:055:57
2611.86:065:55
2711.86:075:54
2811.76:085:52
2911.76:095:50
3011.66:105:49

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.88 kWh/m².

For context, solar energy here swings from a low near 2.1 kWh/m² to a high of 7.99 kWh/m² in June across the year — September's 5.88 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.6Intense
26.5Intense
36.5Intense
46.5Intense
56.4Intense
66.4Intense
76.3Intense
86.3Intense
96.2Intense
106.2Intense
116.1Intense
126.0Intense
136.0Intense
146.0Bright
155.9Bright
165.8Bright
175.8Bright
185.7Bright
195.7Bright
205.6Bright
215.6Bright
225.5Bright
235.5Bright
245.4Bright
255.4Bright
265.3Bright
275.3Bright
285.2Bright
295.1Bright
305.1Bright
Planning a trip in September

Hazard calendar for Agua Caliente

In seasonPeak

None of Agua Caliente's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Agua Caliente's rainy season runs November–March, when most of the year's rain falls.

Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Agua Caliente?

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

9.1
Sightseeing
2nd-best month of the year
8.4
Beach & pool
3rd-best month of the year

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

What to pack for Agua Caliente in September

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

In September, Agua Caliente sees daytime highs around 78°F and nights near 55°F. Worth packing: light clothes and sun protection.

light clothessun protection

Sea temperature near Agua Caliente in September

The nearest coast averages about 58°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 32 mi away) is warmest in September at about 58°F and coldest in April near 53°F.

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

52°54°56°58°60°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°F)Comfort
Jan53Bracing
Feb53Bracing
Mar54Bracing
Apr53Bracing
May53Bracing
Jun54Bracing
Jul56Bracing
Aug58Bracing
Sep58Bracing
Oct57Bracing
Nov55Bracing
Dec54Bracing

UV index in Agua Caliente in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Agua Caliente peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateJun 23UV 10Dec 13UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Extreme
Jul10Extreme
Aug9Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Low

Air quality in Agua Caliente 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 Agua Caliente is worst in September — around 29 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 7 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateSep 1829 µg/m³Jun 127 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun7Good
Jul10Good
Aug25Moderate
Sep29Moderate
Oct27Moderate
Nov16Moderate
Dec12Good
Location & terrain

Where is Agua Caliente?

Agua Caliente sits at 38.3°N, 122.5°W, 154 ft above sea level, in United States. The nearest listed city is Petaluma, 11 mi away.

Topography around Agua Caliente

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

Within 2 miles, the terrain around Agua Caliente has significant variations in elevation — a maximum elevation change of 1,181 ft around an average of 381 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,730 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,895 ft.

The land around Agua Caliente is covered by trees (62%) and grassland (24%) within 2 miles, trees (43%) and grassland (40%) within 10 miles, and trees (32%), grassland (27%) and water (25%) within 50 miles.

2 miles
1,181 ft
10 miles
2,730 ft
50 miles
4,895 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Petaluma 11 mi · Napa 11 mi · Rohnert Park 12 mi · Santa Rosa 15 mi · Novato 16 mi · American Canyon 16 mi · Vallejo 20 mi · Windsor 24 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 Agua Caliente (38.3241°, -122.488°, elevation 154 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).