August weather forecast
Rochester, IL

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Weather in August

The last month of the summer, August, is another warm month in Rochester, Illinois, with temperature in the range of an average low of 64°F (17.8°C) and an average high of 81.9°F (27.7°C).

Temperature

On the advent of August, Rochester's average high-temperature exhibits a minor adjustment to a still moderately hot 81.9°F (27.7°C) from July's 82.8°F (28.2°C). In the month of August, an average of 64°F (17.8°C) marks the low-temperature.

Heat index

For August, the heat index is calculated to be a tropical 87.8°F (31°C). Uninterrupted exposure and activity might result in fatigue, potentially causing heat cramps.
Heat index details are generally centered around shaded locations and a mild breeze. The heat index has the potential to rise by 15 Fahrenheit (8 Celsius) degrees with direct sunshine exposure.
Note: The heat index, also known as 'feels like' or 'real feel', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. The perception of temperature can be subjective, varying based on activity and individual heat sensitivity, influenced by factors like wind, attire, and metabolic variations. Consider that direct sun exposure can intensify the felt heat, adding potentially 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are highly critical for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it's vital to remain hydrated, particularly during prolonged physical activities.

Humidity

The average relative humidity in August in Rochester is 81%.

Rainfall

In Rochester, in August, during 14.5 rainfall days, 2.17" (55mm) of precipitation is typically accumulated. Throughout the year, there are 141.7 rainfall days, and 22.72" (577mm) of precipitation is accumulated.

Snowfall

May through October are months without snowfall in Rochester.

Daylight

The average length of the day in August is 13h and 41min.
On the first day of the month, sunrise is at 5:57 am and sunset at 8:10 pm. On the last day of August, sunrise is at 6:25 am and sunset at 7:30 pm CDT.

Sunshine

In August, the average sunshine is 9.8h.

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 average individuals.
Note: In August, an average UV index of 6 transforms into the following instructions:
Refrain from overexposure. Fair-skinned individuals could burn in under 20 minutes. Remember that UV radiation from the Sun is strongest between 10 a.m. and 4 p.m. Make an effort to limit direct sun exposure during this time. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear.
Updated: Jun 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the temperature in August?

In August, in Rochester, the average high-temperature is 81.9°F (27.7°C), and the average low-temperature is 64°F (17.8°C). The average heat index (a.k.a. 'apparent temperature', 'feels like'), which combines air temperature and relative humidity, in August is calculated to be 87.8°F (31°C).

What is the average humidity in August?

In Rochester, the average relative humidity in August is 81%.

How much does it rain in August?

In Rochester, during August, the rain falls for 14.5 days and regularly aggregates up to 2.17" (55mm) of precipitation.

When it does not snow?

May through October are months without snowfall.

How many hours of daylight does Rochester have in August?

The average day length in August is 13h and 41min.

When are sunrise and sunset in August?

On the first day of August, sunrise is at 5:57 am and sunset at 8:10 pm. On the last day of the month, sunrise is at 6:25 am and sunset at 7:30 pm CDT.

How long on average sun shines in August?

In August, the average sunshine duration is 9.8h.

What are the months with the highest UV index?

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

What is the UV index reading in August in Rochester?

The average daily maximum UV index in August is 6. A UV Index value of 6 to 7 symbolizes a high health risk 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
Rochester, IL

Average temperature in August - Rochester, IL
  • Average high temperature in August: 81.9°F

The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (33.4°F).

  • Average low temperature in August: 64°F

The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (21.4°F).

Average pressure in August
Rochester, IL

Average pressure in August - Rochester, IL
  • Average pressure in August: 29.98"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in August
Rochester, IL

Average wind speed in August - Rochester, IL
  • Average wind speed in August: 6.2mph

The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).

Average humidity in August
Rochester, IL

Average humidity in August - Rochester, IL
  • Average humidity in August: 81%

The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).

Average rainfall in August
Rochester, IL

Average rainfall in August - Rochester, IL
  • Average rainfall in August: 2.17"

The wettest month (with the highest rainfall) is April (2.64").
The driest month (with the least rainfall) is December (1.14").

Average rainfall days in August
Rochester, IL

Average rainfall days in August - Rochester, IL
  • Average rainfall days in August: 14.5 days

The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is February (6.2 days).

Average snowfall in August
Rochester, IL

Average snowfall in August - Rochester, IL
  • Average snowfall in August: 0"

The month with the highest snowfall is February (1.85").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in August
Rochester, IL

Average snowfall days in August - Rochester, IL
  • Average snowfall days in August: 0 days

The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

Average daylight in August /
Average sunshine in August
Rochester, IL

Average daylight in August / Average sunshine in August - Rochester, IL
  • Average daylight in August: 13h and 4min

The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in August: 9h and 5min

The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).

Average sunshine days in August
Rochester, IL

Average sunshine days in August - Rochester, IL
  • Average sunshine days in August: 12.8 days

The month with the most sunshine days is October (18.7 days).
The month with the least sunshine days is July (11 days).

Average UV index in August
Rochester, IL

Average UV index in August - Rochester, IL
  • 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).

Average cloud cover in August
Rochester, IL

Average cloud cover in August - Rochester, IL
  • Average cloud cover in August: 30

The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is June (Cloud cover 29).

Average visibility in August
Rochester, IL

Average visibility in August - Rochester, IL
  • Average visibility in August: 5mi

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

Rochester, Illinois, USA

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