Rancho Cucamonga weather in August
In August, Rancho Cucamonga sees average daytime highs of 91°F and overnight lows near 67°F, with 0.0 in of rain across 0.3 wet days and about 13.3 hours of daylight. It is the 1st-warmest and 12th-wettest month of the year here.
Day-to-day highs hold fairly steady near 91°F through the month. The sky is clear or mostly clear about 90% of the time in August, and the air most often feels comfortable.
Daylight stretches from about 13 h 42 min at the start of August to 12 h 48 min by month's end. Set against the rest of the year, August is Rancho Cucamonga's 1st-clearest and 11th-windiest month. For the whole year in context, see Rancho Cucamonga's year-round climate.
- Daytime high
- 91°
- 1st warmest
- Overnight low
- 67°
- 12th coldest
- Rainfall
- 0.0 in
- 0.3 wet days
- Daylight
- 13 h 18 min
- 5:16 AM – 6:33 PM
- Cloud cover
- 12%
- 1st clearest
- Wind
- 3 mph
- 11th windiest
- Solar energy
- 7.37 kWh/m²
- Travel score
- 4.9
- out of 10
Rancho Cucamonga is suburban city in San Bernardino County, California, United States.
- Density
- 1,692/km²
- people per km²
- Founded
- 1977
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in August
Day-to-day highs hold fairly steady near 91°F through the month.
A typical August day in Rancho Cucamonga reaches about 91°F in the afternoon and slips back to 67°F overnight — a 24°F spread between the day's warmth and the night's chill. On most days the high lands between 84°F and 99°F. Set against its neighbours, August runs about 2°F warmer than July and about 3°F warmer than September.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 | 91 |
| Avg low (°F) | 66 | 66 | 66 | 66 | 66 | 66 | 66 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 67 | 66 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 91 | 66 |
| 2 | 91 | 66 |
| 3 | 91 | 66 |
| 4 | 91 | 66 |
| 5 | 91 | 66 |
| 6 | 91 | 66 |
| 7 | 91 | 66 |
| 8 | 91 | 67 |
| 9 | 91 | 67 |
| 10 | 91 | 67 |
| 11 | 91 | 67 |
| 12 | 91 | 67 |
| 13 | 91 | 67 |
| 14 | 91 | 67 |
| 15 | 91 | 67 |
| 16 | 91 | 67 |
| 17 | 91 | 67 |
| 18 | 91 | 67 |
| 19 | 91 | 67 |
| 20 | 91 | 67 |
| 21 | 91 | 67 |
| 22 | 91 | 67 |
| 23 | 91 | 67 |
| 24 | 91 | 67 |
| 25 | 91 | 67 |
| 26 | 91 | 67 |
| 27 | 91 | 67 |
| 28 | 91 | 67 |
| 29 | 91 | 67 |
| 30 | 91 | 67 |
| 31 | 91 | 66 |
How August really feels in Rancho Cucamonga
Once humidity and wind are folded in, August averages 31 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.
The story in August is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
Rancho Cucamonga 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.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 63° / 42° | 3.8 | 6.6 | 10 | 6.2 |
| Feb | 64° / 44° | 4.4 | 7.4 | 10.7 | 6.2 |
| Mar | 67° / 47° | 2.7 | 6.8 | 11.7 | 6.8 |
| Apr | 71° / 50° | 1.2 | 4.6 | 12.8 | 7.8 |
| May | 76° / 55° | 0.6 | 2.6 | 13.7 | 8.6 |
| Jun | 83° / 60° | 0.1 | 0.5 | 14.2 | 7.8 |
| Jul | 89° / 65° | 0.1 | 0.5 | 14 | 5.5 |
| Aug | 91° / 67° | 0.0 | 0.3 | 13.3 | 4.9 |
| Sep | 88° / 63° | 0.2 | 1.2 | 12.2 | 6.1 |
| Oct | 79° / 56° | 0.9 | 3.1 | 11.1 | 8.3 |
| Nov | 70° / 48° | 1.2 | 3.5 | 10.2 | 7.9 |
| Dec | 62° / 42° | 2.6 | 5.8 | 9.8 | 6.2 |
Cloud cover in August
The sky is clear or mostly clear about 90% of the time in August, the clearest month of the year.
Beyond those clear spells, partly cloudy skies cover about 4% of August, with mostly cloudy or overcast conditions the remaining 5%.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 91 | 92 | 92 | 92 | 93 | 93 | 95 | 95 | 95 | 96 | 96 | 96 | 96 | 96 | 97 | 97 | 97 | 97 | 97 | 96 | 96 | 96 | 95 | 95 | 95 | 95 | 95 | 94 | 94 | 94 | 94 |
| Cloudier (%) | 9 | 8 | 8 | 8 | 7 | 7 | 5 | 5 | 5 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 5 | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 6 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 91 | 9 |
| 2 | 92 | 8 |
| 3 | 92 | 8 |
| 4 | 92 | 8 |
| 5 | 93 | 7 |
| 6 | 93 | 7 |
| 7 | 95 | 5 |
| 8 | 95 | 5 |
| 9 | 95 | 5 |
| 10 | 96 | 4 |
| 11 | 96 | 4 |
| 12 | 96 | 4 |
| 13 | 96 | 4 |
| 14 | 96 | 4 |
| 15 | 97 | 3 |
| 16 | 97 | 3 |
| 17 | 97 | 3 |
| 18 | 97 | 3 |
| 19 | 97 | 3 |
| 20 | 96 | 4 |
| 21 | 96 | 4 |
| 22 | 96 | 4 |
| 23 | 95 | 5 |
| 24 | 95 | 5 |
| 25 | 95 | 5 |
| 26 | 95 | 5 |
| 27 | 95 | 5 |
| 28 | 94 | 6 |
| 29 | 94 | 6 |
| 30 | 94 | 6 |
| 31 | 94 | 6 |
Chance of precipitation in August
Rancho Cucamonga 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 3% on the wettest days.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 3 |
| Rain chance (%) | |
|---|---|
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 1 |
| 9 | 1 |
| 10 | 1 |
| 11 | 1 |
| 12 | 1 |
| 13 | 1 |
| 14 | 1 |
| 15 | 1 |
| 16 | 1 |
| 17 | 1 |
| 18 | 1 |
| 19 | 1 |
| 20 | 1 |
| 21 | 1 |
| 22 | 1 |
| 23 | 1 |
| 24 | 1 |
| 25 | 2 |
| 26 | 2 |
| 27 | 2 |
| 28 | 2 |
| 29 | 2 |
| 30 | 2 |
| 31 | 3 |
Humidity in August
Most of August feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, August lands in the comfortable band about 46% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 19 | 20 | 20 | 21 | 22 | 23 | 23 | 24 | 24 | 25 | 25 | 25 | 25 | 25 | 25 | 25 | 24 | 24 | 24 | 25 | 25 | 26 | 26 | 27 | 28 | 29 | 29 | 30 | 31 | 31 | 32 |
| Comfortable (%) | 47 | 47 | 46 | 46 | 46 | 45 | 45 | 45 | 45 | 45 | 46 | 46 | 46 | 47 | 47 | 48 | 48 | 49 | 49 | 49 | 49 | 49 | 48 | 48 | 47 | 46 | 45 | 45 | 44 | 43 | 43 |
| Humid (%) | 31 | 31 | 31 | 30 | 30 | 29 | 29 | 28 | 28 | 28 | 27 | 27 | 27 | 26 | 26 | 26 | 25 | 25 | 25 | 25 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 24 | 23 | 23 |
| Muggy (%) | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| 1 | 19 | 47 | 31 | 3 |
| 2 | 20 | 47 | 31 | 3 |
| 3 | 20 | 46 | 31 | 3 |
| 4 | 21 | 46 | 30 | 3 |
| 5 | 22 | 46 | 30 | 3 |
| 6 | 23 | 45 | 29 | 3 |
| 7 | 23 | 45 | 29 | 3 |
| 8 | 24 | 45 | 28 | 3 |
| 9 | 24 | 45 | 28 | 3 |
| 10 | 25 | 45 | 28 | 2 |
| 11 | 25 | 46 | 27 | 2 |
| 12 | 25 | 46 | 27 | 2 |
| 13 | 25 | 46 | 27 | 2 |
| 14 | 25 | 47 | 26 | 2 |
| 15 | 25 | 47 | 26 | 2 |
| 16 | 25 | 48 | 26 | 2 |
| 17 | 24 | 48 | 25 | 2 |
| 18 | 24 | 49 | 25 | 2 |
| 19 | 24 | 49 | 25 | 2 |
| 20 | 25 | 49 | 25 | 2 |
| 21 | 25 | 49 | 24 | 1 |
| 22 | 26 | 49 | 24 | 1 |
| 23 | 26 | 48 | 24 | 1 |
| 24 | 27 | 48 | 24 | 1 |
| 25 | 28 | 47 | 24 | 1 |
| 26 | 29 | 46 | 24 | 1 |
| 27 | 29 | 45 | 24 | 2 |
| 28 | 30 | 45 | 24 | 2 |
| 29 | 31 | 44 | 24 | 2 |
| 30 | 31 | 43 | 23 | 2 |
| 31 | 32 | 43 | 23 | 2 |
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.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| 1 | 3 | calm |
| 2 | 3 | calm |
| 3 | 3 | calm |
| 4 | 3 | calm |
| 5 | 3 | calm |
| 6 | 3 | calm |
| 7 | 3 | calm |
| 8 | 3 | calm |
| 9 | 3 | calm |
| 10 | 3 | calm |
| 11 | 3 | calm |
| 12 | 3 | calm |
| 13 | 3 | calm |
| 14 | 3 | calm |
| 15 | 3 | calm |
| 16 | 3 | calm |
| 17 | 3 | calm |
| 18 | 3 | calm |
| 19 | 3 | calm |
| 20 | 3 | calm |
| 21 | 3 | calm |
| 22 | 3 | calm |
| 23 | 3 | calm |
| 24 | 3 | calm |
| 25 | 3 | calm |
| 26 | 3 | calm |
| 27 | 3 | calm |
| 28 | 3 | calm |
| 29 | 3 | calm |
| 30 | 3 | calm |
| 31 | 3 | calm |
Sunrise & sunset in August
Daylight runs from about 13 h 42 min at the start of August to 12 h 48 min by month's end. The lit band spans sunrise to sunset each day.
Days shrink by about 54 minutes over August. Sunrise moves from 5:05 AM to 5:27 AM, and sunset from 6:48 PM to 6:14 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 13.7 | 13.7 | 13.7 | 13.6 | 13.6 | 13.6 | 13.6 | 13.5 | 13.5 | 13.5 | 13.4 | 13.4 | 13.4 | 13.3 | 13.3 | 13.3 | 13.3 | 13.2 | 13.2 | 13.2 | 13.1 | 13.1 | 13.1 | 13.0 | 13.0 | 13.0 | 12.9 | 12.9 | 12.9 | 12.8 | 12.8 |
| Sunrise (AM) | 5:05 | 5:06 | 5:06 | 5:07 | 5:08 | 5:09 | 5:09 | 5:10 | 5:11 | 5:12 | 5:12 | 5:13 | 5:14 | 5:15 | 5:15 | 5:16 | 5:17 | 5:17 | 5:18 | 5:19 | 5:20 | 5:20 | 5:21 | 5:22 | 5:23 | 5:23 | 5:24 | 5:25 | 5:26 | 5:26 | 5:27 |
| Sunset (PM) | 6:48 | 6:47 | 6:46 | 6:45 | 6:44 | 6:44 | 6:43 | 6:42 | 6:41 | 6:40 | 6:38 | 6:37 | 6:36 | 6:35 | 6:34 | 6:33 | 6:32 | 6:31 | 6:29 | 6:28 | 6:27 | 6:26 | 6:24 | 6:23 | 6:22 | 6:21 | 6:19 | 6:18 | 6:17 | 6:15 | 6:14 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 13.7 | 5:05 | 6:48 |
| 2 | 13.7 | 5:06 | 6:47 |
| 3 | 13.7 | 5:06 | 6:46 |
| 4 | 13.6 | 5:07 | 6:45 |
| 5 | 13.6 | 5:08 | 6:44 |
| 6 | 13.6 | 5:09 | 6:44 |
| 7 | 13.6 | 5:09 | 6:43 |
| 8 | 13.5 | 5:10 | 6:42 |
| 9 | 13.5 | 5:11 | 6:41 |
| 10 | 13.5 | 5:12 | 6:40 |
| 11 | 13.4 | 5:12 | 6:38 |
| 12 | 13.4 | 5:13 | 6:37 |
| 13 | 13.4 | 5:14 | 6:36 |
| 14 | 13.3 | 5:15 | 6:35 |
| 15 | 13.3 | 5:15 | 6:34 |
| 16 | 13.3 | 5:16 | 6:33 |
| 17 | 13.3 | 5:17 | 6:32 |
| 18 | 13.2 | 5:17 | 6:31 |
| 19 | 13.2 | 5:18 | 6:29 |
| 20 | 13.2 | 5:19 | 6:28 |
| 21 | 13.1 | 5:20 | 6:27 |
| 22 | 13.1 | 5:20 | 6:26 |
| 23 | 13.1 | 5:21 | 6:24 |
| 24 | 13.0 | 5:22 | 6:23 |
| 25 | 13.0 | 5:23 | 6:22 |
| 26 | 13.0 | 5:23 | 6:21 |
| 27 | 12.9 | 5:24 | 6:19 |
| 28 | 12.9 | 5:25 | 6:18 |
| 29 | 12.9 | 5:26 | 6:17 |
| 30 | 12.8 | 5:26 | 6:15 |
| 31 | 12.8 | 5:27 | 6:14 |
Solar energy in August
Average shortwave solar energy reaching the ground each day in August, about 7.37 kWh/m².
For context, solar energy here swings from a low near 2.98 kWh/m² to a high of 8.15 kWh/m² in June across the year — August's 7.37 kWh/m² falls in the middle.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 7.6 | 7.6 | 7.6 | 7.6 | 7.6 | 7.6 | 7.6 | 7.6 | 7.5 | 7.5 | 7.5 | 7.5 | 7.5 | 7.4 | 7.4 | 7.4 | 7.3 | 7.3 | 7.3 | 7.3 | 7.2 | 7.2 | 7.2 | 7.1 | 7.1 | 7.0 | 7.0 | 7.0 | 6.9 | 6.9 | 6.8 |
| Level | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense | Intense |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 7.6 | Intense |
| 2 | 7.6 | Intense |
| 3 | 7.6 | Intense |
| 4 | 7.6 | Intense |
| 5 | 7.6 | Intense |
| 6 | 7.6 | Intense |
| 7 | 7.6 | Intense |
| 8 | 7.6 | Intense |
| 9 | 7.5 | Intense |
| 10 | 7.5 | Intense |
| 11 | 7.5 | Intense |
| 12 | 7.5 | Intense |
| 13 | 7.5 | Intense |
| 14 | 7.4 | Intense |
| 15 | 7.4 | Intense |
| 16 | 7.4 | Intense |
| 17 | 7.3 | Intense |
| 18 | 7.3 | Intense |
| 19 | 7.3 | Intense |
| 20 | 7.3 | Intense |
| 21 | 7.2 | Intense |
| 22 | 7.2 | Intense |
| 23 | 7.2 | Intense |
| 24 | 7.1 | Intense |
| 25 | 7.1 | Intense |
| 26 | 7.0 | Intense |
| 27 | 7.0 | Intense |
| 28 | 7.0 | Intense |
| 29 | 6.9 | Intense |
| 30 | 6.9 | Intense |
| 31 | 6.8 | Intense |
Is August a good time to visit Rancho Cucamonga?
Our two travel scores rate August for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
August is a reasonable time to visit Rancho Cucamonga for sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Rancho Cucamonga in August
From August's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In August, Rancho Cucamonga sees daytime highs around 91°F and nights near 67°F. Pack light clothes and sun protection.
Sea temperature near Rancho Cucamonga in August
The nearest coast averages about 69°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 37 mi away) is warmest in August at about 69°F and coldest in February near 59°F.
It's comfortable for a long swim from Jul 13 to Sep 28 — about 2.6 months when the water holds above 68°F.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 59 | 59 | 59 | 60 | 63 | 65 | 68 | 69 | 69 | 67 | 64 | 60 |
| Comfort | Cool | Cool | Cool | Cool | Cool | Cool | Refreshing | Refreshing | Refreshing | Cool | Cool | Cool |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 59 | Cool |
| Feb | 59 | Cool |
| Mar | 59 | Cool |
| Apr | 60 | Cool |
| May | 63 | Cool |
| Jun | 65 | Cool |
| Jul | 68 | Refreshing |
| Aug | 69 | Refreshing |
| Sep | 69 | Refreshing |
| Oct | 67 | Cool |
| Nov | 64 | Cool |
| Dec | 60 | Cool |
UV index in Rancho Cucamonga in August
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 Rancho Cucamonga peaks around July 12 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 16 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 4 | 5 | 5 | 8 | 8 | 11 | 11 | 10 | 8 | 6 | 3 | 3 |
| Level | Moderate | Moderate | Moderate | Very high | Very high | Extreme | Extreme | Extreme | Very high | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 4 | Moderate |
| Feb | 5 | Moderate |
| Mar | 5 | Moderate |
| Apr | 8 | Very high |
| May | 8 | Very high |
| Jun | 11 | Extreme |
| Jul | 11 | Extreme |
| Aug | 10 | Extreme |
| Sep | 8 | Very high |
| Oct | 6 | High |
| Nov | 3 | Moderate |
| Dec | 3 | Moderate |
Air quality in Rancho Cucamonga in August
Average fine-particle pollution (PM2.5) through the year — so you can see where August falls, not just the annual average.
Air quality in Rancho Cucamonga is worst in September — around 49 µg/m³ PM2.5 (poor), about 4.0× the cleanest month (May, 12 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 18 | 19 | 19 | 17 | 12 | 17 | 19 | 32 | 49 | 21 | 21 | 18 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Poor | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 18 | Moderate |
| Feb | 19 | Moderate |
| Mar | 19 | Moderate |
| Apr | 17 | Moderate |
| May | 12 | Moderate |
| Jun | 17 | Moderate |
| Jul | 19 | Moderate |
| Aug | 32 | Moderate |
| Sep | 49 | Poor |
| Oct | 21 | Moderate |
| Nov | 21 | Moderate |
| Dec | 18 | Moderate |
Where is Rancho Cucamonga?
Rancho Cucamonga sits at 34.1°N, 117.6°W, 1,207 ft above sea level, in United States. The nearest listed city is Upland, 3.1 mi away.
Topography around Rancho Cucamonga
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Rancho Cucamonga.
Within 2 miles, the terrain around Rancho Cucamonga has only modest variations in elevation — a maximum elevation change of 522 ft around an average of 1,240 ft above sea level; within 10 miles, extreme variations in elevation — a maximum elevation change of 8,238 ft; within 50 miles, extreme variations in elevation — a maximum elevation change of 11,424 ft.
The land around Rancho Cucamonga is covered by artificial surfaces (84%) within 2 miles, artificial surfaces (54%) and shrubs (21%) within 10 miles, and artificial surfaces (25%), shrubs (23%) and grassland (21%) within 50 miles.
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
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 Rancho Cucamonga (34.1064°, -117.5931°, elevation 1,207 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).