July weather forecast
Naperville, IL

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A covered bridge over a river along the famous Naperville Riverwalk in Naperville, Illinois
A covered bridge over a river along the famous Naperville Riverwalk in Naperville, Illinois

Weather in July

No month is hotter in Naperville than July, reaching high averages of 81.7°F (27.6°C) and lows of 65.1°F (18.4°C). While summer is in full swing, the weather tends to be humid, creating some discomfort for residents and visitors. Despite the heat, the city stays vibrant during the day with several outdoor and indoor events that cater to every interest.

Temperature

July is the warmest month, with an average high-temperature of 81.7°F (27.6°C) and an average low-temperature of 65.1°F (18.4°C).

Heat index

The heat index in July is computed to be a tropical 87.8°F (31°C). Enduring exposure and unrelenting activity might cause a state of weariness, potentially leading to heat cramps.
One should be cognizant that the heat index values are tailored for shaded spots and mild winds. With exposure to direct sunshine, the heat index could climb by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', marries air temperature and humidity to produce a value illustrating perceived warmth. One's perception of weather can be shaped by other factors, involving metabolic differences, pregnancy, and physical exertion. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly important for children. Children typically face more danger than adults as their sweat production is usually lower. Additionally, the bigger skin surface compared to their small size and the increased heat due to their activeness exacerbate the risk.

Humidity

In July, the average relative humidity is 80%.

Rainfall

In Naperville, in July, during 17.3 rainfall days, 2.05" (52mm) of precipitation is typically accumulated. In Naperville, during the entire year, the rain falls for 132.2 days and collects up to 16.22" (412mm) of precipitation.

Snowfall

In Naperville, snow does not fall in May through September.

Daylight

In July, the average length of the day is 14h and 51min.
On the first day of July, sunrise is at 5:22 am and sunset at 8:31 pm. On the last day of the month, sunrise is at 5:46 am and sunset at 8:11 pm CDT.

Sunshine

The months with the most sunshine are July and August, with an average of 10h of sunshine.

UV index

June through August, with an average maximum UV index of 6, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for ordinary individuals.
Note: A maximum high daily UV index of 6 during July translates into the following directions:
Use protective steps and abide by sun safety guidelines. Safeguarding against skin and eye harm is necessary. Between 10 a.m. and 4 p.m., the Sun emits the most powerful UV radiation. Limit direct exposure to the Sun during these hours. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage.
Updated: Aug 28, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the hottest in Naperville?

In Naperville, the average highest temperatures are observed in July, with a high of 81.7°F (27.6°C) and a low of 65.1°F (18.4°C).

What is the temperature in July?

In July, the average high-temperature and low-temperature are 81.7°F (27.6°C) and 65.1°F (18.4°C) respectively. In July, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which represents the influence of relative humidity on air temperature, is computed to be 87.8°F (31°C).

What is the average humidity in July?

In July, the average relative humidity is 80%.

How much does it rain in July?

In July, in Naperville, the rain falls for 17.3 days. Throughout July, 2.05" (52mm) of precipitation is accumulated.

When it does not snow?

In Naperville, snow does not fall in May through September.

How many hours of daylight does Naperville have in July?

In July, the average day length is 14h and 51min.

When are sunrise and sunset in July?

On the first day of July, sunrise is at 5:22 am and sunset at 8:31 pm. On the last day of the month, sunrise is at 5:46 am and sunset at 8:11 pm CDT.

What is the month with the most sunshine?

The months with the most sunshine are July and August, with an average of 10h of sunshine.

How long on average sun shines in July?

In July, the average sunshine duration is 10h.

What are the months with the highest UV index?

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

What is the UV index intensity in July?

In July, the average daily maximum UV index is 6. A UV Index estimate of 6 to 7 represents a high health risk from unprotected exposure to 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 July
Naperville, IL

Average temperature in July - Naperville, IL
  • Average high temperature in July: 81.7°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.4°F).

  • Average low temperature in July: 65.1°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 (17.1°F).

Average pressure in July
Naperville, IL

Average pressure in July - Naperville, IL
  • Average pressure in July: 29.97"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in July
Naperville, IL

Average wind speed in July - Naperville, IL
  • Average wind speed in July: 6.2mph

The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6mph).

Average humidity in July
Naperville, IL

Average humidity in July - Naperville, IL
  • Average humidity in July: 80%

The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (73%).

Average rainfall in July
Naperville, IL

Average rainfall in July - Naperville, IL
  • Average rainfall in July: 2.05"

The wettest month (with the highest rainfall) is May (2.09").
The driest month (with the least rainfall) is December (0.71").

Average rainfall days in July
Naperville, IL

Average rainfall days in July - Naperville, IL
  • Average rainfall days in July: 17.3 days

The month with the highest number of rainy days is July (17.3 days).
The month with the least rainy days is February (4.4 days).

Average snowfall in July
Naperville, IL

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

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

Average snowfall days in July
Naperville, IL

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

The month with the highest number of snowfall days is January (11.1 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in July / Average sunshine in July - Naperville, IL
  • Average daylight in July: 14h and 5min

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 July: 10h and 0min

The months with the most sunshine are July and August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

Average sunshine days in July
Naperville, IL

Average sunshine days in July - Naperville, IL
  • Average sunshine days in July: 10.2 days

The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (10.2 days).

Average UV index in July
Naperville, IL

Average UV index in July - Naperville, IL
  • Average UV index in July: 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 and December (UV index 1).

Average cloud cover in July
Naperville, IL

Average cloud cover in July - Naperville, IL
  • Average cloud cover in July: 32

The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 31).

Average visibility in July
Naperville, IL

Average visibility in July - Naperville, IL
  • Average visibility in July: 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).

Naperville, Illinois, USA

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