Alum Rock weather in August

In August, Alum Rock sees average daytime highs of 82°F and overnight lows near 57°F, with 0.0 in of rain across 0.3 wet days and about 13.4 hours of daylight. It is the 1st-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 82°F through the month. The sky is clear or mostly clear about 91% of the time in August, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of August to 12 h 54 min by month's end. Set against the rest of the year, August is Alum Rock's 1st-clearest and 11th-windiest month. For the whole year in context, see Alum Rock's year-round climate.

Daytime high
82°
1st warmest
Overnight low
57°
12th coldest
Rainfall
0.0 in
0.3 wet days
Daylight
13 h 24 min
5:28 AM – 6:55 PM
Cloud cover
10%
1st clearest
Wind
3 mph
11th windiest
Solar energy
7.21 kWh/m²
Travel score
8.8
out of 10

Alum Rock is census-designated place in Santa Clara County, California.

Density
7,068/km²
people per km²

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 82°F through the month.

A typical August day in Alum Rock reaches about 82°F in the afternoon and slips back to 57°F overnight — a 25°F spread between the day's warmth and the night's chill. On most days the high lands between 75°F and 91°F. Set against its neighbours, August runs on par with July and about 2°F warmer than September.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18258
28258
38258
48258
58258
68258
78258
88258
98258
108258
118258
128258
138258
148258
158258
168258
178257
188257
198257
208257
218257
228257
238257
248257
258257
268257
278257
288257
298257
308257
318257

Alum Rock weather by month

How August compares with the rest of the year at a glance. August is the 1st-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan56° / 40°4.49.19.74.1
Feb58° / 42°4.49.210.64.4
Mar61° / 44°3.39.211.75.4
Apr65° / 45°1.65.712.96.7
May71° / 49°0.83.4148.1
Jun77° / 53°0.20.814.59.1
Jul82° / 57°0.10.214.38.8
Aug82° / 57°0.00.313.48.8
Sep80° / 56°0.10.612.38.9
Oct73° / 51°1.02.8118.6
Nov63° / 44°1.95.7106.2
Dec56° / 40°3.98.89.54.0

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 91% of the time in August, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 5% of August, with mostly cloudy or overcast conditions the remaining 5%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
1964
2964
3955
4955
5955
6955
7955
8955
9955
10955
11955
12955
13955
14955
15955
16955
17955
18955
19955
20955
21955
22964
23964
24964
25964
26964
27964
28964
29964
30964
31964

Chance of precipitation in August

Any precipitation

Alum Rock gets around 0.0 in of rain over 0.3 wet days in August, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 1% and peaks near 1% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
11
21
31
41
51
61
71
81
91
101
111
121
131
141
151
161
171
181
191
201
211
221
231
241
251
261
271
281
291
301
311

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the dry band about 87% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)
188120
288120
388120
488120
588120
688120
789110
889110
989110
1089110
1189110
1289110
1389110
1489110
1588111
1687121
1787121
1887121
1986131
2086131
2186131
2286131
2386131
2486131
2586131
2686131
2786131
2886131
2986131
3087121
3187121

Wind in August

Winds average 3 mph in August.

Across August, daily wind ranges from about 3 mph on the calmest days to 3 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
13calm
23calm
33calm
43calm
53calm
63calm
73calm
83calm
93calm
103calm
113calm
123calm
133calm
143calm
153calm
163calm
173calm
183calm
193calm
203calm
213calm
223calm
233calm
243calm
253calm
263calm
273calm
283calm
293calm
303calm
313calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 13 h 54 min at the start of August to 12 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 60 minutes over August. Sunrise moves from 5:15 AM to 5:41 AM, and sunset from 7:12 PM to 6:34 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.95:157:12
213.95:167:11
313.95:177:10
413.95:187:09
513.85:187:08
613.85:197:07
713.85:207:06
813.75:217:04
913.75:227:03
1013.75:237:02
1113.65:247:01
1213.65:247:00
1313.65:256:59
1413.55:266:57
1513.55:276:56
1613.45:286:55
1713.45:296:54
1813.45:306:52
1913.35:316:51
2013.35:316:50
2113.35:326:48
2213.25:336:47
2313.25:346:45
2413.25:356:44
2513.15:366:43
2613.15:376:41
2713.05:376:40
2813.05:386:38
2913.05:396:37
3012.95:406:35
3112.95:416:34

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 7.21 kWh/m².

For context, solar energy here swings from a low near 2.36 kWh/m² to a high of 7.99 kWh/m² in June across the year — August's 7.21 kWh/m² sits near the top of that range.

02468151015202531
Solar energy (kWh/m²)Level
17.6Intense
27.6Intense
37.6Intense
47.5Intense
57.5Intense
67.5Intense
77.5Intense
87.5Intense
97.4Intense
107.4Intense
117.4Intense
127.3Intense
137.3Intense
147.3Intense
157.3Intense
167.2Intense
177.2Intense
187.2Intense
197.1Intense
207.1Intense
217.1Intense
227.0Intense
237.0Intense
247.0Intense
256.9Intense
266.9Intense
276.9Intense
286.8Intense
296.8Intense
306.7Intense
316.7Intense
Planning a trip in August

Hazard calendar for Alum Rock

In seasonPeak

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

Alum Rock's rainy season runs December–March, when most of the year's rain falls.

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

Is August a good time to visit Alum Rock?

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

8.8
Sightseeing
3rd-best month of the year
9.2
Beach & pool
1st-best month of the year

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

What to pack for Alum Rock in August

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

In August, Alum Rock sees daytime highs around 82°F and nights near 57°F. Pack light clothes and sun protection.

light clothessun protection

Sea temperature near Alum Rock in August

The nearest coast averages about 59°F in August — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 30 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 Alum Rock in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Alum Rock peaks around June 23 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 23UV 10Dec 15UV 2
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar5Moderate
Apr7High
May8Very high
Jun10Extreme
Jul10Extreme
Aug10Very high
Sep6High
Oct5High
Nov2Moderate
Dec2Moderate

Air quality in Alum Rock in August

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Alum Rock 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 Alum Rock?

Alum Rock sits at 37.4°N, 121.8°W, 151 ft above sea level, in United States. The nearest listed city is San Jose, 4.3 mi away.

Topography around Alum Rock

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

Within 2 miles, the terrain around Alum Rock has significant variations in elevation — a maximum elevation change of 1,129 ft around an average of 240 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,921 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,373 ft.

The land around Alum Rock is covered by artificial surfaces (73%) within 2 miles, artificial surfaces (42%), grassland (33%) and trees (22%) within 10 miles, and grassland (29%), trees (25%) and water (25%) within 50 miles.

2 miles
1,129 ft
10 miles
3,921 ft
50 miles
4,373 ft
treesgrasslandcroplandartificial surfaceswaterwetland
August weather nearby: San Jose 4.3 mi · Milpitas 6.2 mi · Santa Clara 6.8 mi · Campbell 8.7 mi · Sunnyvale 11 mi · Cupertino 12 mi · Los Gatos 12 mi · Saratoga 13 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 Alum Rock (37.3661°, -121.8272°, elevation 151 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).