August weather forecast
Flagstaff, AZ

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The brown iconic clock tower in the city of Flagstaff, Arizona, with the street signs of Birch Avenue and San Francisco Street
The brown iconic clock tower in the city of Flagstaff, Arizona, with the street signs of Birch Avenue and San Francisco Street

Weather in August

August introduces a subtle change in weather conditions in Flagstaff. The rainfall decreases slightly from its July peak, marking the end of the heavy rain phase. However, the city still experiences a healthy dose of sunshine, presenting a nice balance of sun and showers. Temperatures start to weaken, leading to more comfortable days and nights. August, therefore, marks the transitional phase from monsoon to pre-autumn weather.

Temperature

Flagstaff observes a minor difference in average high-temperatures between July's 82.8°F (28.2°C) and August's 81°F (27.2°C). Flagstaff, during August nights, observes an average temperature of 59.7°F (15.4°C).

Heat index

In August, the heat index is calculated to be 80.6°F (27°C). If one sustains activity during exposure, it could lead to a sense of fatigue, with a chance of heat cramps.
Evaluating the heat index requires understanding its values in the shade and with gentle winds. If directly exposed to the sun, the heat index could rise by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', is a value derived by merging air temperature with the humidity to convey how the climate feels. The individual's temperature perception can be influenced by numerous factors such as metabolic variations, physical activity, and clothing. Consider the fact that direct sun exposure can influence how hot one feels, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly relevant to babies and toddlers. Young individuals usually face greater risks than adults as their sweat production is less. Also, their larger skin surface relative to their small bodies and the high heat generation due to their activity contributes to their vulnerability.

Humidity

The average relative humidity in August is 45%.

Rainfall

In August, the rain falls for 14 days. Throughout August, 1.93" (49mm) of precipitation is accumulated. Throughout the year, there are 74.8 rainfall days, and 12.56" (319mm) of precipitation is accumulated.

Snowfall

In Flagstaff, snow does not fall in June through September.

Daylight

The average length of the day in August is 13h and 26min.
On the first day of August in Flagstaff, sunrise is at 5:36 am and sunset at 7:29 pm. On the last day of the month, sunrise is at 5:59 am and sunset at 6:54 pm MST.

Sunshine

June and August, with an average of 12.2h of sunshine, are months with the most sunshine in Flagstaff.

UV index

The months with the highest UV index are June through August, with an average maximum UV index of 6. A UV Index estimate of 6 to 7 represents a high health risk from unprotected exposure to Sun's UV rays for the average person.
Note: In August, a daily maximum UV index of 6 leads to the following instructions:
Stand by precautions and apply sun safety measures. Evading sunburn is of great importance. Avoid direct exposure to the Sun between 10 a.m. and 4 p.m., the peak period for UV radiation, noting that objects like parasols or canopies might not offer complete sun protection. Enhance your sun protection with tightly woven, yet airy clothing.
Updated: Feb 9, 2024 | Published by: Weather U.S. | Resources

Frequently asked questions

What are the temperatures in Flagstaff in August?

An average high-temperature, in August, in Flagstaff, is 81°F (27.2°C) and the average low-temperature is 59.7°F (15.4°C). In August, the average heat index (a.k.a. 'real feel', 'feels like'), which combines air temperature and relative humidity, is calculated to be 80.6°F (27°C).

What is the average humidity in August in Flagstaff?

In August, the average relative humidity in Flagstaff is 45%.

How many days does it rain in August in Flagstaff?

In Flagstaff, in August, during 14 rainfall days, 1.93" (49mm) of precipitation is typically accumulated.

When it does not snow in Flagstaff?

In Flagstaff, Arizona, snow does not fall in June through September.

What is the average length of the day in August in Flagstaff?

In Flagstaff, Arizona, the average day length in August is 13h and 26min.

When are sunrise and sunset in August in Flagstaff?

On the first day of August in Flagstaff, Arizona, sunrise is at 5:36 am and sunset at 7:29 pm. On the last day of the month, sunrise is at 5:59 am and sunset at 6:54 pm MST.

What are the months with the most sunshine in Flagstaff?

June and August, with an average of 12.2h of sunshine, are months with the most sunshine in Flagstaff, Arizona.

How many hours of sunshine does Flagstaff have in August?

The average sunshine duration in August in Flagstaff is 12.2h.

What is the month with the highest UV index in Flagstaff?

The months with the highest UV index in Flagstaff, Arizona, are June through August, with an average maximum UV index of 6.

How high is the UV index in August in Flagstaff?

In Flagstaff, the average daily maximum UV index in August is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in August
Flagstaff, AZ

Average temperature in August - Flagstaff, AZ
  • Average high temperature in August: 81°F

The warmest month (with the highest average high temperature) is July (82.8°F).
The months with the lowest average high temperature are January and December (42.6°F).

  • Average low temperature in August: 59.7°F

The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is December (24.8°F).

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Average pressure in August
Flagstaff, AZ

Average pressure in August - Flagstaff, AZ
  • Average pressure in August: 29.94"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).

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Average wind speed in August
Flagstaff, AZ

Average wind speed in August - Flagstaff, AZ
  • Average wind speed in August: 5.8mph

The windiest month (with the highest average wind speed) is April (9.6mph).
The calmest month (with the lowest average wind speed) is August (5.8mph).

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Average humidity in August
Flagstaff, AZ

Average humidity in August - Flagstaff, AZ
  • Average humidity in August: 45%

The month with the highest relative humidity is January (66%).
The month with the lowest relative humidity is June (24%).

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Average rainfall in August
Flagstaff, AZ

Average rainfall in August - Flagstaff, AZ
  • Average rainfall in August: 1.93"

The wettest month (with the highest rainfall) is July (2.56").
The driest month (with the least rainfall) is June (0.24").

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Average rainfall days in August
Flagstaff, AZ

Average rainfall days in August - Flagstaff, AZ
  • Average rainfall days in August: 14 days

The month with the highest number of rainy days is July (16.2 days).
The months with the least rainy days are February and November (2.5 days).

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Average snowfall in August
Flagstaff, AZ

Average snowfall in August - Flagstaff, AZ
  • Average snowfall in August: 0"

The month with the highest snowfall is December (7.36").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in August
Flagstaff, AZ

Average snowfall days in August - Flagstaff, AZ
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is December (7.4 days).
The months with the least snowfall days are June, July and August (0 days).

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Average daylight in August /
Average sunshine in August
Flagstaff, AZ

Average daylight in August / Average sunshine in August - Flagstaff, AZ
  • Average daylight in August: 13h and 2min

The month with the longest days is June (Average daylight: 14h and 30min).
The month with the shortest days is December (Average daylight: 9h and 48min).

  • Average sunshine in August: 12h and 1min

The months with the most sunshine are June and August (Average sunshine: 12h and 12min).
The month with the least sunshine is December (Average sunshine: 6h and 48min).

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Average sunshine days in August
Flagstaff, AZ

Average sunshine days in August - Flagstaff, AZ
  • Average sunshine days in August: 12.3 days

The month with the most sunshine days is June (25.8 days).
The month with the least sunshine days is July (11.4 days).

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Average UV index in August
Flagstaff, AZ

Average UV index in August - Flagstaff, AZ
  • Average UV index in August: 6

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in August
Flagstaff, AZ

Average cloud cover in August - Flagstaff, AZ
  • Average cloud cover in August: 13

The month with the most cloud cover is December (Cloud cover 24).
The month with the least cloud cover is June (Cloud cover 7).

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Average visibility in August
Flagstaff, AZ

Average visibility in August - Flagstaff, AZ
  • Average visibility in August: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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Flagstaff, Arizona, USA

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