August weather forecastJohnston, IA
August
Weather in August
August brings closeness to the close of summer in Johnston. Despite this transition, the weather remains warm, with mild winds adding an enjoyable rhythmic pattern to the days. The rain starts to increase slightly again, preparing the ground for the upcoming autumnal season. This month is an exceptional time to enjoy green spaces that are abundant with life and color. August is an invitation to experience the waning days of summer while peeking into the approaching fall.Temperature
August's onset sees an average high-temperature of a still moderately hot 81.3°F (27.4°C), exhibiting a slight fluctuation from the previous month. Johnston, in August, experiences an average temperature of 62.2°F (16.8°C) at night.Heat index
The average heat index in August is appraised at a hot 87.8°F (31°C). Long-lasting exposure and activity potentially induce a sense of weariness, with the risk of heat cramps.Heat index determinations are made taking into account the shade and light air movements. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is a value derived by merging air temperature with the humidity to convey how the climate feels. The individual's impression of temperature can be affected by numerous factors such as metabolic variations, physical exertion, and attire. 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 extremely significant for babies and toddlers. Young ones often disregard the necessity to rest and hydrate. Thirst usually indicates advanced dehydration - hence, it is key to stay hydrated, particularly during ongoing physical activities.
Humidity
In Johnston, Iowa, the average relative humidity in August is 79%.Rainfall
In Johnston, in August, it is raining for 12.3 days, with typically 1.81" (46mm) of accumulated precipitation. Throughout the year, there are 114.6 rainfall days, and 15.51" (394mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall.Daylight
In August, the average length of the day is 13h and 48min.On the first day of August, sunrise is at 6:09 am and sunset at 8:32 pm. On the last day of the month, sunrise is at 6:40 am and sunset at 7:49 pm CDT.
Sunshine
In August, the average sunshine is 9.9h.UV index
In August, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the average person.Note: An average UV index of 5 in August transforms into this advice:
Make use of precautions - Shielding skin and eyes from injury is a requirement. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in August
Johnston, IA
- Average high temperature in August: 81.3°F
The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (27.9°F).
- Average low temperature in August: 62.2°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (14.4°F).
Average pressure in August
Johnston, 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 (29.88"Hg).
Average wind speed in August
Johnston, IA
- Average wind speed in August: 7mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in August
Johnston, IA
- Average humidity in August: 79%
The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is October (70%).
Average rainfall in August
Johnston, IA
- Average rainfall in August: 1.81"
The wettest months (with the highest rainfall) are May and June (2.52").
The driest month (with the least rainfall) is January (0.47").
Average rainfall days in August
Johnston, IA
- Average rainfall days in August: 12.3 days
The month with the highest number of rainy days is May (16.3 days).
The month with the least rainy days is February (3.5 days).
Average snowfall in August
Johnston, IA
- Average snowfall in August: 0"
The month with the highest snowfall is January (2.2").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in August
Johnston, IA
- Average snowfall days in August: 0 days
The month with the highest number of snowfall days is January (8.4 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in August /
Average sunshine in August
Johnston, IA
- Average daylight in August: 13h and 48min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in August: 9h and 54min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 18min).
Average sunshine days in August
Johnston, IA
- Average sunshine days in August: 15.6 days
The month with the most sunshine days is December (22.8 days).
The month with the least sunshine days is June (11.2 days).
Average UV index in August
Johnston, IA
- Average UV index in August: 5
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in August
Johnston, IA
- Average cloud cover in August: 30
The month with the most cloud cover is January (Cloud cover 53).
The month with the least cloud cover is September (Cloud cover 28).
Average visibility in August
Johnston, IA
- Average visibility in August: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
