Livermore weather in September

In September, Livermore sees average daytime highs of 81°F and overnight lows near 56°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 11th-wettest month of the year here.

Highs ease over the month, from about 83°F in the first days to 79°F by the end. The sky is clear or mostly clear about 87% 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 42 min by month's end. Set against the rest of the year, September is Livermore's 3rd-clearest and 7th-windiest month. For the whole year in context, see Livermore's year-round climate.

Daytime high
81°
3rd warmest
Overnight low
56°
10th coldest
Rainfall
0.1 in
0.5 wet days
Daylight
12 h 12 min
5:54 AM – 6:09 PM
Cloud cover
14%
3rd clearest
Wind
5 mph
7th windiest
Solar energy
6.09 kWh/m²
Travel score
8.7
out of 10

Livermore is city in Alameda County, California, United States.

Density
1,264/km²
people per km²
Founded
1869

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 83°F in the first days to 79°F by the end.

A typical September day in Livermore reaches about 81°F in the afternoon and slips back to 56°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 73°F and 90°F. Set against its neighbours, September runs about 3°F cooler than August and about 7°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18358
28358
38358
48357
58357
68257
78257
88257
98257
108257
118257
128156
138156
148156
158156
168156
178156
188156
198056
208056
218056
228055
238055
248055
258055
267955
277955
287955
297955
307855

Livermore weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan56° / 41°3.49.49.74.0
Feb59° / 43°3.38.810.54.7
Mar63° / 45°2.68.711.75.9
Apr68° / 47°1.35.212.97.2
May73° / 51°0.63148.4
Jun80° / 55°0.20.814.68.8
Jul84° / 58°0.00.214.37.8
Aug83° / 58°0.10.313.57.8
Sep81° / 56°0.10.512.38.7
Oct74° / 52°0.82.8118.6
Nov63° / 45°1.65.6106.3
Dec56° / 41°3.18.89.44.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 87% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 6% of September, with mostly cloudy or overcast conditions the remaining 7%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1973
2973
3973
4973
5973
6964
7964
8964
9964
10964
11955
12955
13955
14946
15946
16937
17928
18928
19928
20919
21919
22919
239010
249010
259010
269010
278911
288911
298911
308911

Chance of precipitation in September

Any precipitation

Livermore 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 4% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
41
51
61
71
81
91
101
111
121
132
142
152
162
172
182
192
202
212
222
233
243
253
263
273
284
294
304

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 85% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
179192
280182
381172
481172
582162
682162
782162
883152
983152
1083152
1184151
1284151
1384151
1484151
1584151
1685150
1785150
1885150
1985150
2085150
2186140
2286140
2386140
2487130
2587130
2688120
2789110
2889110
2990100
309190

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 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 72 minutes over September. Sunrise moves from 5:41 AM to 6:07 AM, and sunset from 6:32 PM to 5:46 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:416:32
212.85:426:31
312.85:436:29
412.75:446:28
512.75:456:26
612.65:466:25
712.65:466:23
812.65:476:21
912.55:486:20
1012.55:496:18
1112.45:506:17
1212.45:516:15
1312.45:526:13
1412.35:526:12
1512.35:536:10
1612.25:546:09
1712.25:556:07
1812.25:566:05
1912.15:576:04
2012.15:586:02
2112.05:596:00
2212.05:595:59
2311.96:005:57
2411.96:015:56
2511.96:025:54
2611.86:035:52
2711.86:045:51
2811.76:055:49
2911.76:065:48
3011.76:075:46

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.09 kWh/m².

For context, solar energy here swings from a low near 2.25 kWh/m² to a high of 8.21 kWh/m² in June across the year — September's 6.09 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
16.8Intense
26.8Intense
36.7Intense
46.7Intense
56.6Intense
66.6Intense
76.5Intense
86.5Intense
96.4Intense
106.4Intense
116.3Intense
126.3Intense
136.2Intense
146.2Intense
156.1Intense
166.1Intense
176.0Intense
186.0Bright
195.9Bright
205.8Bright
215.8Bright
225.7Bright
235.7Bright
245.6Bright
255.6Bright
265.5Bright
275.5Bright
285.4Bright
295.3Bright
305.3Bright
Planning a trip in September

Is September a good time to visit Livermore?

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

8.7
Sightseeing
2nd-best month of the year
8.9
Beach & pool
3rd-best month of the year

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

What to pack for Livermore in September

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

In September, Livermore sees daytime highs around 81°F and nights near 56°F. Pack light clothes and sun protection.

light clothessun protection

Sea temperature near Livermore in September

The nearest coast averages about 59°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 39 mi away) is warmest in August at about 59°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°JanFebMarAprMayJunJulAugSepOctNovDecbracingcool
Sea temperature (°F)Comfort
Jan54Bracing
Feb54Bracing
Mar54Bracing
Apr54Bracing
May54Bracing
Jun55Bracing
Jul57Bracing
Aug59Bracing
Sep59Bracing
Oct58Bracing
Nov56Bracing
Dec55Bracing

UV index in Livermore 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 Livermore peaks around June 22 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 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 22UV 10Dec 15UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar4Moderate
Apr7High
May8Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Moderate

Air quality in Livermore 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 Livermore is worst in August — around 34 µg/m³ PM2.5 (moderate), about 4.9× the cleanest month (June, 7 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateAug 1832 µg/m³Jun 157 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun7Good
Jul9Good
Aug34Moderate
Sep16Moderate
Oct14Moderate
Nov15Moderate
Dec12Good
Location & terrain

Where is Livermore?

Livermore sits at 37.7°N, 121.8°W, 492 ft above sea level, in United States. The nearest listed city is Pleasanton, 6.2 mi away.

Topography around Livermore

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

Within 2 miles, the terrain around Livermore has only modest variations in elevation — a maximum elevation change of 259 ft around an average of 509 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,064 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,452 ft.

The land around Livermore is covered by artificial surfaces (62%) and grassland (21%) within 2 miles, grassland (67%) within 10 miles, and grassland (30%) and trees (28%) within 50 miles.

2 miles
259 ft
10 miles
3,064 ft
50 miles
4,452 ft
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Pleasanton 6.2 mi · Dublin 9.3 mi · San Ramon 13 mi · Union City 15 mi · Fremont 15 mi · Danville 16 mi · Hayward 17 mi · Castro Valley 17 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 Livermore (37.6819°, -121.768°, elevation 492 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).