August weather forecast
Derby, IA

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Weather in August

The last month of the summer, August, is also a moderately hot month in Derby, Iowa, with an average temperature varying between 62.8°F (17.1°C) and 81.7°F (27.6°C).

Temperature

The transition from July to August brings an average high-temperature of a still warm 81.7°F (27.6°C), barely different from July's 83.1°F (28.4°C). During August, Derby consistently records a temperature low averaging a comfortable 62.8°F (17.1°C).

Heat index

The heat index in August is evaluated at a tropical 87.8°F (31°C). With sustained exposure and activity, exhaustion becomes probable, resulting in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Direct sunlight exposure may result in a rise of the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'felt air temperature', combines both the air temperature and the humidity level to give a perceived human temperature. An individual's perception of weather can be swayed by a variety of elements including metabolic differences, pregnancy status, and their level of physical exertion. Be mindful that being in direct sunlight might mean feeling hotter, with the heat index rising by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are primarily vital for children. In general, younger individuals are at greater risk than adults because they tend to sweat less. Also, having a larger skin surface to body size ratio and greater heat production due to their active behavior contribute to this danger.

Humidity

The average relative humidity in August in Derby is 79%.

Rainfall

In Derby, in August, during 12.7 rainfall days, 2.32" (59mm) of precipitation is typically accumulated. Throughout the year, there are 131.1 rainfall days, and 25.71" (653mm) of precipitation is accumulated.

Snowfall

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

Daylight

In Derby, Iowa, the average length of the day in August is 13h and 46min.
On the first day of the month, sunrise is at 6:10 am and sunset at 8:29 pm. On the last day of August, sunrise is at 6:40 am and sunset at 7:47 pm CDT.

Sunshine

In Derby, the average sunshine in August is 9.7h.

UV index

The months with the highest UV index in Derby are June through August, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for the ordinary person.
Note: In August, the maximum UV index of 6 suggests these recommendations:
Apply measures and align with sun safety principles. Safeguarding against skin and eye injury is pivotal. Avoid direct sunlight between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. Keep in mind that shade structures may not provide complete protection. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average August temperature in Derby?

In Derby, 81.7°F (27.6°C) is the average high-temperature and 62.8°F (17.1°C) is the average low-temperature during August. In August, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, is evaluated at 87.8°F (31°C).

What is the average humidity in August in Derby?

In Derby, the average relative humidity in August is 79%.

How many days does it rain in August in Derby?

In Derby, Iowa, during August, the rain falls for 12.7 days and regularly aggregates up to 2.32" (59mm) of precipitation.

When it does not snow in Derby?

June through September are months without snowfall in Derby, Iowa.

How many hours of daylight does Derby have in August?

The average day length in August in Derby is 13h and 46min.

What time are sunrise and sunset in August in Derby?

On the first day of August in Derby, Iowa, sunrise is at 6:10 am and sunset at 8:29 pm. On the last day of the month, sunrise is at 6:40 am and sunset at 7:47 pm CDT.

How long on average sun shines in August in Derby?

In Derby, Iowa, the average sunshine duration in August is 9.7h.

When is the highest UV index in Derby?

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

How high is the UV index in August in Derby?

The average daily maximum UV index in August in Derby is 6. A UV Index value of 6 to 7 symbolizes a high health threat from exposure to Sun's UV rays.
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
Derby, IA

Average temperature in August - Derby, IA
  • Average high temperature in August: 81.7°F

The warmest month (with the highest average high temperature) is July (83.1°F).
The month with the lowest average high temperature is January (29.3°F).

  • Average low temperature in August: 62.8°F

The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (16°F).

Average pressure in August
Derby, IA

Average pressure in August - Derby, IA
  • Average pressure in August: 29.96"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).

Average wind speed in August
Derby, IA

Average wind speed in August - Derby, IA
  • Average wind speed in August: 7.1mph

The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (7.1mph).

Average humidity in August
Derby, IA

Average humidity in August - Derby, IA
  • Average humidity in August: 79%

The month with the highest relative humidity is June (83%).
The month with the lowest relative humidity is October (72%).

Average rainfall in August
Derby, IA

Average rainfall in August - Derby, IA
  • Average rainfall in August: 2.32"

The wettest month (with the highest rainfall) is June (3.74").
The driest month (with the least rainfall) is January (0.94").

Average rainfall days in August
Derby, IA

Average rainfall days in August - Derby, IA
  • Average rainfall days in August: 12.7 days

The month with the highest number of rainy days is May (16.7 days).
The month with the least rainy days is January (4.7 days).

Average snowfall in August
Derby, IA

Average snowfall in August - Derby, IA
  • Average snowfall in August: 0"

The month with the highest snowfall is February (4.13").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in August
Derby, IA

Average snowfall days in August - Derby, IA
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is January (10.2 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in August /
Average sunshine in August
Derby, IA

Average daylight in August / Average sunshine in August - Derby, IA
  • Average daylight in August: 13h and 5min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in August: 9h and 4min

The month with the most sunshine is July (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).

Average sunshine days in August
Derby, IA

Average sunshine days in August - Derby, IA
  • Average sunshine days in August: 16 days

The month with the most sunshine days is November (19.3 days).
The month with the least sunshine days is June (10.7 days).

Average UV index in August
Derby, IA

Average UV index in August - Derby, IA
  • Average UV index in August: 6

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).

Average cloud cover in August
Derby, IA

Average cloud cover in August - Derby, IA
  • Average cloud cover in August: 30

The month with the most cloud cover is January (Cloud cover 54).
The months with the least cloud cover are July and August (Cloud cover 30).

Average visibility in August
Derby, IA

Average visibility in August - Derby, IA
  • Average visibility in August: 5mi

The months with the highest visibility are February, March, April, May, June, July, September, October, November and December (6mi).
The months with the lowest visibility are January and August (5mi).

Derby, Iowa, USA

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