Chico weather in September

In September, Chico sees average daytime highs of 88°F and overnight lows near 60°F, with 0.3 in of rain across 1.2 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 92°F in the first days to 85°F by the end. The sky is clear or mostly clear about 84% 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 Chico's 3rd-clearest and 11th-windiest month. For the whole year in context, see Chico's year-round climate.

Daytime high
88°
4th warmest
Overnight low
60°
9th coldest
Rainfall
0.3 in
1.2 wet days
Daylight
12 h 18 min
5:54 AM – 6:09 PM
Cloud cover
16%
3rd clearest
Wind
5 mph
11th windiest
Solar energy
5.93 kWh/m²
Travel score
5.8
out of 10

Chico is city in Butte County, California, United States.

Density
1,416/km²
people per km²
Founded
1860

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 92°F in the first days to 85°F by the end.

A typical September day in Chico reaches about 88°F in the afternoon and slips back to 60°F overnight — a 28°F spread between the day's warmth and the night's chill. On most days the high lands between 77°F and 98°F. Set against its neighbours, September runs about 6°F cooler than August and about 11°F warmer than October.

60°80°100°151015202530
Avg high (°F)Avg low (°F)
19264
29263
39263
49263
59163
69162
79162
89162
99062
109062
119061
128961
138961
148961
158860
168860
178860
188860
198760
208759
218759
228759
238659
248658
258658
268558
278558
288557
298457
308457

How September really feels in Chico

Once humidity and wind are folded in, September averages 11 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
11
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Chico weather by month

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

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan57° / 40°7.211.20.59.53.9
Feb60° / 42°6.910.20.710.44.6
Mar64° / 45°5.910.90.411.75.8
Apr70° / 49°2.97.40.2137.0
May80° / 55°1.95.1014.27.6
Jun89° / 63°0.61.8014.85.2
Jul96° / 67°0.00.1014.53.2
Aug94° / 65°0.10.3013.63.7
Sep88° / 60°0.31.2012.35.8
Oct77° / 52°2.03.8010.98.1
Nov64° / 44°4.180.29.85.9
Dec56° / 40°7.911.40.59.23.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 84% 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 9%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1946
2955
3946
4946
5946
6937
7937
8937
9937
10937
11928
12919
13919
14919
15919
16919
17919
18919
19919
20919
21919
22919
238911
248911
258911
268911
278911
288812
298713
308713

Chance of precipitation in September

Any precipitation

Chico gets around 0.3 in of rain over 1.2 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 4% and peaks near 8% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
42
52
62
72
82
92
102
113
123
133
143
154
164
174
184
195
205
215
226
236
246
256
267
277
287
297
308

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 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
19631
29631
39631
49631
59631
69631
79541
89541
99541
109541
119541
129730
139730
149730
159730
169730
179730
189820
199820
209820
219820
229910
239910
249910
259910
269910
279910
289910
299910
309910

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 5:40 AM to 6:08 AM, and sunset from 6:35 PM to 5:46 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:406:35
212.95:416:33
312.85:416:31
412.85:426:30
512.75:436:28
612.75:446:26
712.75:456:25
812.65:466:23
912.65:476:21
1012.55:486:20
1112.55:496:18
1212.45:506:16
1312.45:516:15
1412.35:526:13
1512.35:536:11
1612.35:546:09
1712.25:556:08
1812.25:566:06
1912.15:576:04
2012.15:586:03
2112.05:596:01
2212.06:005:59
2311.96:015:57
2411.96:025:56
2511.96:035:54
2611.86:045:52
2711.86:055:51
2811.76:065:49
2911.76:075:47
3011.66:085:46

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 1.94 kWh/m² to a high of 8.24 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
136.0Intense
146.0Intense
155.9Bright
165.9Bright
175.8Bright
185.8Bright
195.7Bright
205.7Bright
215.6Bright
225.6Bright
235.5Bright
245.4Bright
255.4Bright
265.3Bright
275.3Bright
285.2Bright
295.2Bright
305.1Bright
Planning a trip in September

Hazard calendar for Chico

In seasonPeak

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

Chico'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 Chico?

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

5.8
Sightseeing
5th-best month of the year
8.6
Beach & pool
1st-best month of the year

September is a reasonable time to visit Chico for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Chico in September

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

In September, Chico sees daytime highs around 88°F and nights near 60°F. Pack light clothes. Worth having: sun protection.

light clothessun protection

UV index in Chico 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 Chico peaks around June 22 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 22UV 10Dec 13UV 2
UV index (midday)Level
Jan2Moderate
Feb3Moderate
Mar5Moderate
Apr6High
May9Very high
Jun10Very high
Jul10Very high
Aug8Very high
Sep6High
Oct5Moderate
Nov2Low
Dec2Low

Air quality in Chico 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 Chico is worst in July — around 64 µg/m³ PM2.5 (unhealthy), about 8.2× the cleanest month (December, 8 µg/m³).

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

020406080JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateUnhealthyModerateJul 2363 µg/m³Dec 238 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb11Good
Mar13Moderate
Apr13Moderate
May10Good
Jun10Good
Jul64Unhealthy
Aug59Unhealthy
Sep63Unhealthy
Oct17Moderate
Nov37Poor
Dec8Good
Location & terrain

Where is Chico?

Chico sits at 39.7°N, 121.8°W, 197 ft above sea level, in United States. The nearest listed city is Paradise, 12 mi away.

Topography around Chico

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

Within 2 miles, the terrain around Chico has only modest variations in elevation — a maximum elevation change of 128 ft around an average of 207 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,860 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,772 ft.

The land around Chico is covered by trees (62%) and artificial surfaces (29%) within 2 miles, trees (51%) and grassland (33%) within 10 miles, and trees (52%) and grassland (32%) within 50 miles.

2 miles
128 ft
10 miles
1,860 ft
50 miles
7,772 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Paradise 12 mi · Oroville 21 mi · Yuba City 42 mi · South Yuba City 43 mi · Linda 44 mi · Lincoln 65 mi · Redding 66 mi · Clearlake 68 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 Chico (39.7285°, -121.8375°, elevation 197 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).