Climateby Month

Fontana, CA weather in August

NOAA 1991-2020 normals and daily records · Fontana all year

In August, Fontana sees highs around 95°F and lows around 65°F: hot and dry. Expect about 1 wet day. It is one of the warmest months in Fontana. Plan outdoor time for mornings and evenings.

Normal high
95°F
Normal low
65°F
Wet days
1
0.09 in total
Muggy days
0
dew point 65°F+

How August changes from start to finish

Normal values at the start and end of August
August 1August 31
Normal high95°F95°F
Normal low65°F65°F
Chance of a wet day3%3%
Sunrise / sunset6:01 am / 7:51 pm6:22 am / 7:17 pm
Daylight13.8 h12.9 h

Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Pacific Time).

A typical August day

  1. 6 am65°Fdew point 56°F
  2. 9 am81°Fdew point 55°F
  3. Noon92°Fdew point 52°F
  4. 3 pm93°Fdew point 53°F
  5. 6 pm84°Fdew point 53°F
  6. 9 pm73°Fdew point 55°F

NOAA hourly normals (local standard time) from March AFB (17 mi away); average wind 6 mph; clear or few clouds in 85% of daytime hours, mostly cloudy or overcast in 8%.

What kind of days to expect

  • Comfortable dayshigh 65-80°F and dew point under 60°F0 of 31
  • Hot dayshigh 90°F or more24 of 31
  • Muggy daysdaily mean dew point 65°F or more0 of 31
  • Wet daysat least 0.01 in of rain or melted snow1 of 31
  • Notable rainat least 0.10 in0 of 31
  • Freezing nightslow 32°F or below0 of 31

Average days per August, counted from daily records for each year 1991-2020.

Rain in August

Normal precipitation is 0.09 in; a dry August brings about 0.0 in and a wet one about 0.03 in (25th and 75th percentiles). Days with half an inch or more are rare.

How August varies from year to year

  • Warmest August, 1991-20202020: average high 98°F
  • Coolest August2002: average high 90°F
  • Wettest August2014: 1.3 in
  • Driest August1991: no measurable precipitation
  • Highest reading112°F (August 31, 2017)
  • Lowest reading56°F (August 8, 2011)

From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.

August compared with July and September

JulyAugustSeptember
Normal high94°F95°F91°F
Normal low65°F65°F64°F
Wet days111
Comfortable days104
Daylight14.2 h13.4 h12.4 h

Highs change by +1°F from July and -4°F into September.

Nearby alternatives in August

How Fontana ranks in August

  • Normal high51st warmest of 378 cities; 13th of 60 in California
  • Wet days47th driest of 378
  • Comfortable days221st most of 341

What to pack for Fontana in August

  • Light, breathable clothing – highs near 95°F
  • Layers – afternoons near 95°F but nights near 65°F

Heating and cooling

August has 0 heating degree days and 467 cooling degree days (base 65°F), 14% of the year's total heating and cooling demand.

Questions

How hot is Fontana in August?

The normal high is 95°F and the normal low is 65°F. From 1991 to 2020 the hottest August reading was 112°F (August 31, 2017).

Does it rain a lot in Fontana in August?

About 1 days in August have at least 0.01 in of precipitation, and the normal total is 0.09 in. The wettest August in 1991-2020 was in 2014 (1.3 in); the driest was in 1991, with no measurable precipitation.

Is August a good time to visit Fontana?

August ranks 12th of 12 months on our comfort score for Fontana (41 out of 100). It has almost no comfortable days and about 24 days at 90°F or hotter. The best months are March, April and May.

Where the numbers come from

  • Temperature: Ontario Intl Airport (USW00003102), 9.8 mi WSW of the city center, 949 ft (287 ft lower than the city). NOAA normals and daily records, 1991-2020.
  • Rain: Redlands (USC00047306), 14 mi ESE of the city center, 1,410 ft (174 ft higher than the city). NOAA normals and daily records, 1991-2020.
  • Snowfall and snow depth: Riverside Citrus Exp (USC00047473), 9.6 mi SSE of the city center, 986 ft (250 ft lower than the city). NOAA normals and daily records, 1991-2020.
  • Frost dates: Riverside Muni Airport (USW00003171), 9.7 mi S of the city center, 805 ft (431 ft lower than the city). NOAA normals and daily records, 1991-2020.
  • Humidity and wind by hour and cloud cover: March AFB (USW00023119), 17 mi SE of the city center, 1,516 ft (280 ft higher than the city). NOAA normals and daily records, 1991-2020.
  • Daily humidity and wind: March Air Reserve Base (722860-23119), 17 mi SE of the city center, 1,536 ft (300 ft higher than the city). Hourly observations, 1991-2020.