Susanville weather in September

In September, Susanville sees average daytime highs of 75°F and overnight lows near 48°F, with 0.6 in of precipitation across 3 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 80°F in the first days to 71°F by the end. The sky is clear or mostly clear about 72% 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 Susanville's 3rd-clearest and 10th-windiest month. For the whole year in context, see Susanville's year-round climate.

Daytime high
75°
3rd warmest
Overnight low
48°
10th coldest
Precipitation
0.6 in
3 wet days
Daylight
12 h 18 min
5:49 AM – 6:05 PM
Cloud cover
24%
3rd clearest
Wind
5 mph
10th windiest
Solar energy
5.93 kWh/m²
Travel score
8.5
out of 10

Susanville is city in and county seat of Lassen County, California, United States.

Density
733/km²
people per km²
Founded
1900

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 80°F in the first days to 71°F by the end.

A typical September day in Susanville reaches about 75°F in the afternoon and slips back to 48°F overnight — a 27°F spread between the day's warmth and the night's chill. On most days the high lands between 63°F and 85°F. Set against its neighbours, September runs about 8°F cooler than August and about 13°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18152
28051
38051
48051
57951
67951
77950
87850
97850
107750
117749
127749
137649
147649
157648
167548
177548
187447
197447
207447
217347
227347
237346
247346
257246
267246
277145
287145
297044
307044

How September really feels in Susanville

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 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
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Susanville 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 daysSnow daysDaylight (hours)Travel score
Jan38° / 22°3.59.69.19.40.0
Feb41° / 24°3.39.69.110.40.1
Mar46° / 28°3.210.59.211.71.3
Apr53° / 32°2.09.46133.2
May64° / 40°1.98.51.814.26.0
Jun75° / 48°0.94.80.314.88.0
Jul85° / 55°0.42.7014.66.9
Aug84° / 54°0.42.6013.67.3
Sep75° / 48°0.630.112.38.5
Oct62° / 39°1.14.51.210.96.4
Nov47° / 29°2.27.55.59.81.6
Dec37° / 22°3.810.59.69.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 72% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 13%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1928
2919
3919
49010
59010
69010
78812
88812
98812
108713
118713
128713
138713
148614
158614
168614
178515
188614
198614
208614
218614
228614
238515
248515
258515
268416
278317
288317
298218
308218

Chance of precipitation in September

Any precipitationSnow

Susanville gets around 0.6 in of rain and snow over 3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 10% and peaks near 12% on the wettest days, and about 0 day brings snow.

0%10%20%30%151015202530
Rain chance (%)Snow chance (%)
180
280
380
490
590
690
7100
8100
9100
10100
11100
12110
13110
14110
15110
16110
17110
18110
19110
20110
21110
22111
23111
24111
25111
26111
27121
28121
29122
30122

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
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

Wind in September

Winds average 5 mph in September.

Across September, daily wind ranges from about 5 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
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

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 5:34 AM to 6:03 AM, and sunset from 6:30 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:346:30
212.95:356:29
312.95:366:27
412.85:376:25
512.85:386:24
612.75:396:22
712.75:406:20
812.65:416:19
912.65:426:17
1012.55:436:15
1112.55:446:14
1212.45:456:12
1312.45:466:10
1412.45:476:08
1512.35:486:07
1612.35:496:05
1712.25:506:03
1812.25:516:01
1912.15:526:00
2012.15:535:58
2112.05:545:56
2212.05:555:54
2311.95:565:53
2411.95:575:51
2511.95:585:49
2611.85:595:47
2711.86:005:46
2811.76:015:44
2911.76:025:42
3011.66:035:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.93 kWh/m².

For context, solar energy here swings from a low near 2.08 kWh/m² to a high of 8.22 kWh/m² in July across the year — September's 5.93 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.7Intense
26.7Intense
36.6Intense
46.6Intense
56.5Intense
66.5Intense
76.4Intense
86.3Intense
96.3Intense
106.2Intense
116.2Intense
126.1Intense
136.1Intense
146.0Intense
155.9Bright
165.9Bright
175.8Bright
185.8Bright
195.7Bright
205.7Bright
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 Susanville

In seasonPeak

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

Susanville's rainy season runs November–May, 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 Susanville?

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

8.5
Sightseeing
1st-best month of the year
7.0
Beach & pool
3rd-best month of the year

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

What to pack for Susanville in September

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

In September, Susanville sees daytime highs around 75°F and nights near 48°F. Worth packing: light clothes and sun protection. About 3 days see rain.

light clothessun protection

UV index in Susanville 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 Susanville peaks around June 23 at about 11 (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 11Dec 13UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5High
Apr7Very high
May9Very high
Jun11Extreme
Jul11Extreme
Aug9Very high
Sep6High
Oct5Moderate
Nov2Moderate
Dec2Moderate

Air quality in Susanville 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 Susanville is worst in August — around 148 µg/m³ PM2.5 (unhealthy), about 33.7× the cleanest month (December, 4 µg/m³).

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

0306090120150JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateUnhealthyGoodAug 16136 µg/m³Dec 195 µg/m³
PM2.5 (µg/m³)Level
Jan5Good
Feb6Good
Mar8Good
Apr9Good
May8Good
Jun7Good
Jul55Poor
Aug148Unhealthy
Sep45Poor
Oct8Good
Nov6Good
Dec4Good
Location & terrain

Where is Susanville?

Susanville sits at 40.4°N, 120.7°W, 4,186 ft above sea level, in United States. The nearest listed city is Paradise, 68 mi away.

Topography around Susanville

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

Within 2 miles, the terrain around Susanville has only modest variations in elevation — a maximum elevation change of 735 ft around an average of 4,308 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,652 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 8,543 ft.

The land around Susanville is covered by grassland (58%) and trees (22%) within 2 miles, trees (50%) and grassland (45%) within 10 miles, and trees (50%) and grassland (40%) within 50 miles.

2 miles
735 ft
10 miles
3,652 ft
50 miles
8,543 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Paradise 68 mi · Spanish Springs 73 mi · Sun Valley 73 mi · Reno 76 mi · Sparks 77 mi · Chico 79 mi · Oroville 79 mi · Truckee 79 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 Susanville (40.4163°, -120.653°, elevation 4,186 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).