July weather forecast
Decatur, IL

Weather in July

July, the same as June, is another warm summer month in Decatur, Illinois, with average temperature ranging between min 65.7°F (18.7°C) and max 82°F (27.8°C).

Temperature

With an average high-temperature of 82°F (27.8°C) and an average low-temperature of 65.7°F (18.7°C), July is the warmest month.

Heat index

In July, the average heat index is evaluated at a tropical 90°F (32.2°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'felt air temperature', 'feels like', or 'real feel', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Additional factors like wind, pregnancy, clothing, and activity influence one's weather impression. Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

With an average relative humidity of 84%, July is the most humid month in Decatur, Illinois.

Rainfall

In Decatur, Illinois, during July, the rain falls for 14.8 days and regularly aggregates up to 1.54" (39mm) of precipitation. In Decatur, during the entire year, the rain falls for 130.2 days and collects up to 16.34" (415mm) of precipitation.

Snowfall

May through October are months without snowfall in Decatur.

Daylight

The average length of the day in Decatur is 14.7h.

Sunshine

In July, the average sunshine is 10.1h.

UV index

Months with the highest UV index are June through August, with an average maximum UV index of 6. A UV Index value of 6 to 7 symbolizes a high health risk from the exposure to the Sun's UV rays for the ordinary person.
Note: In July, the average maximum UV index of 6 translate into the following recommendations:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. 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.
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FAQ

What is the warmest month in Decatur?

With an average high-temperature of 82°F (27.8°C) and an average low-temperature of 65.7°F (18.7°C), July is the warmest month in Decatur.

What is the temperature in July in Decatur?

The average high-temperature, in July, in Decatur, is 82°F (27.8°C), while the average low-temperature is 65.7°F (18.7°C). The average heat index (a.k.a. 'real feel', 'apparent temperature'), which factors the actual air temperature with the relative humidity, in July is evaluated at 90°F (32.2°C).

What is the most humid month in Decatur?

With an average relative humidity of 84%, July is the most humid month in Decatur, Illinois.

What is the average humidity in July in Decatur?

The average relative humidity in July in Decatur is 84%.

How much does it rain in Decatur in July?

In Decatur, in July, it is raining for 14.8 days, with typically 1.54" (39mm) of accumulated precipitation.

When it does not snow in Decatur?

May through October are months without snowfall in Decatur, Illinois.

What is the average length of the day in July in Decatur?

In July, the average length of the day in Decatur, Illinois, is 14.7h.

How many hours of sunshine does Decatur have in July?

The average sunshine in July in Decatur, Illinois, is 10.1h.

When is the highest UV index in Decatur?

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

What is the UV index reading in July in Decatur?

In July, the average daily maximum UV index in Decatur is 6. A UV Index value of 6 to 7 symbolizes a high hazard to health from unsafe exposure to the Sun's UV rays.

Average temperature in July
Decatur, IL

Average temperature in July - Decatur, IL
  • Average high temperature in July: 82°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (32.9°F).

  • Average low temperature in July: 65.7°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 (21.2°F).

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Average pressure in July
Decatur, IL

Average pressure in July - Decatur, IL
  • Average pressure in July: 29.97"

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

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Average wind speed in July
Decatur, IL

Average wind speed in July - Decatur, IL
  • Average wind speed in July: 6.3mph

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 (6.3mph).

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Average humidity in July
Decatur, IL

Average humidity in July - Decatur, IL
  • Average humidity in July: 84%

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

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Average rainfall in July
Decatur, IL

Average rainfall in July - Decatur, IL
  • Average rainfall in July: 1.54"

The wettest month (with the highest rainfall) is May (2.01").
The driest months (with the least rainfall) are February and December (0.87").

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Average rainfall days in July
Decatur, IL

Average rainfall days in July - Decatur, IL
  • Average rainfall days in July: 14.8 days

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is February (5.8 days).

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Average snowfall in July
Decatur, IL

Average snowfall in July - Decatur, IL
  • Average snowfall in July: 0"

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

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Average snowfall days in July
Decatur, IL

Average snowfall days in July - Decatur, IL
  • Average snowfall days in July: 0 days

The month with the highest number of snowfall days is January (7.2 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in July /
Average sunshine in July
Decatur, IL

Average daylight in July / Average sunshine in July - Decatur, IL
  • Average daylight in July: 14.7h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in July: 10.1h

The month with the most sunshine is June (Average sunshine: 10.4h).
The month with the least sunshine is January (Average sunshine: 4.1h).

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Average sunshine days in July
Decatur, IL

Average sunshine days in July - Decatur, IL
  • Average sunshine days in July: 13.3 days

The month with the most sunshine days is October (19.8 days).
The month with the least sunshine days is May (11.5 days).

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Average UV index in July
Decatur, IL

Average UV index in July - Decatur, IL
  • Average UV index in July: 6

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

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Average cloud cover in July
Decatur, IL

Average cloud cover in July - Decatur, IL
  • Average cloud cover in July: 31

The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is September (Cloud cover 29).

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Average visibility in July
Decatur, IL

Average visibility in July - Decatur, IL
  • Average visibility in July: 5mi

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

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