May weather forecast
Harrisburg, IL

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Weather in May

The weather in May introduces the early signs of Summer in Harrisburg, Illinois. Temperature variance is noticeable throughout May, ranging from 58.1°F (14.5°C) to 75.6°F (24.2°C). This month typically grants a balance of weather conditions, with comfortable, warm days set against relatively cooler nights. Vibrant foliage accentuates the landscapes of Harrisburg as rainfall for the month decreases from April. A progressive rise in temperatures towards the end of May sets the stage for the full onset of Summer.

Temperature

Harrisburg sees an increase in the average high-temperature with the arrival of May, moving from April's comfortable 66.4°F (19.1°C) to a moderately hot 75.6°F (24.2°C). The average temperature during May nights dips to a mild 58.1°F (14.5°C).

Humidity

May is the most humid month, with an average relative humidity of 79%.

Rainfall

In Harrisburg, Illinois, in May, during 18.5 rainfall days, 3.86" (98mm) of precipitation is typically accumulated. In Harrisburg, during the entire year, the rain falls for 158.6 days and collects up to 36.02" (915mm) of precipitation.

Snowfall

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

Daylight

The average length of the day in May in Harrisburg is 14h and 13min.
On the first day of the month, sunrise is at 5:57 am and sunset at 7:44 pm. On the last day of May, in Harrisburg, sunrise is at 5:33 am and sunset at 8:09 pm CDT.

Sunshine

In Harrisburg, the average sunshine in May is 9.2h.

UV index

The months with the highest UV index are May through August, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high health risk from unsafe exposure to UV radiation for the ordinary person.
Note: During May, 6 as the daily maximum UV index converts into the following advice:
Continue precautions and advocate sun safety advice. Deterrence of sunburn is indispensable. Avoid direct exposure to the Sun between 10 a.m. and 4 p.m., the peak period for UV radiation, noting that objects like parasols or canopies might not offer complete sun protection. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key.
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Frequently asked questions

What is the temperature in May in Harrisburg?

During May, Harrisburg experiences an average high-temperature of 75.6°F (24.2°C) and a low-temperature of 58.1°F (14.5°C).

What is the most humid month in Harrisburg?

With an average relative humidity of 79%, May is the most humid month in Harrisburg.

What is the average humidity in May in Harrisburg?

The average relative humidity in May in Harrisburg is 79%.

How many days does it rain in May in Harrisburg?

In May, in Harrisburg, the rain falls for 18.5 days. Throughout May, 3.86" (98mm) of precipitation is accumulated.

When it does not snow in Harrisburg?

May through September are months without snowfall in Harrisburg, Illinois.

Does it snow in Harrisburg in May?

In May, in Harrisburg, Illinois, it doesn't snow. April is the latest month when it typically snows.

How many hours of daylight does Harrisburg have in May?

In Harrisburg, the average day length in May is 14h and 13min.

When is the sunrise / sunset in May in Harrisburg?

On the first day of May in Harrisburg, Illinois, sunrise is at 5:57 am and sunset at 7:44 pm. On the last day of the month, sunrise is at 5:33 am and sunset at 8:09 pm CDT.

How long on average sun shines in May in Harrisburg?

In May, the average sunshine duration in Harrisburg is 9.2h.

What is the month with the highest UV index in Harrisburg?

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

How high is the UV index in May in Harrisburg?

In May, the average daily maximum UV index is 6. A UV Index reading of 6 to 7 represents a high hazard to health from unsafe exposure to Sun's UV rays.
Today
Tomorrow
Long-term
YearJFMAMayJJASOND
Apr
May
Jun
Average high temperature
66.4°F 19.1°C
75.6°F 24.2°C
84.7°F 29.3°C
Average low temperature
48.7°F 9.3°C
58.1°F 14.5°C
66.2°F 19°C
Average pressure
29.96" 761mmHg
29.97" 761mmHg
29.94" 760mmHg
Average wind speed
9.3mph 15km/h
7.8mph 12.6km/h
6.6mph 10.6km/h
Average max. wind speed
10mph 16.1km/h
8.5mph 13.7km/h
7.1mph 11.4km/h
Average wind speed gusts
15.2mph 24.5km/h
12.7mph 20.4km/h
10.8mph 17.4km/h
Average humidity
77%
79%
76%
Average rainfall
4.8" 122mm
3.86" 98mm
3.46" 88mm
Average rainfall days
16.6
18.5
15.6
Average snowfall
0.16" 4mm
0" 0mm
0" 0mm
Average snowfall days
0.6
0
0
Average daylight
13h 1min
14h 1min
14h 4min
Average sunshine
8h 4min
9h 1min
10h 4min
Average sunshine days
11.5
9.9
12.1
Average UV index
4
6
6
Average cloud cover
41%
38%
28%
Average visibility
6mi 9.7km
6mi 9.7km
6mi 9.7km

Average temperature in May
Harrisburg, IL

Average temperature in May - Harrisburg, IL
  • Average high temperature in May: 75.6°F

The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (39.7°F).

  • Average low temperature in May: 58.1°F

The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.2°F).

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Average pressure in May
Harrisburg, IL

Average pressure in May - Harrisburg, IL
  • Average pressure in May: 29.97"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).

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Average wind speed in May
Harrisburg, IL

Average wind speed in May - Harrisburg, IL
  • Average wind speed in May: 7.8mph

The windiest months (with the highest average wind speed) are January and February (9.4mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).

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Average humidity in May
Harrisburg, IL

Average humidity in May - Harrisburg, IL
  • Average humidity in May: 79%

The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (70%).

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Average rainfall in May
Harrisburg, IL

Average rainfall in May - Harrisburg, IL
  • Average rainfall in May: 3.86"

The wettest month (with the highest rainfall) is April (4.8").
The driest month (with the least rainfall) is September (1.57").

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Average rainfall days in May
Harrisburg, IL

Average rainfall days in May - Harrisburg, IL
  • Average rainfall days in May: 18.5 days

The month with the highest number of rainy days is May (18.5 days).
The month with the least rainy days is November (9.7 days).

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Average snowfall in May
Harrisburg, IL

Average snowfall in May - Harrisburg, IL
  • Average snowfall in May: 0"

The month with the highest snowfall is January (1.73").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in May
Harrisburg, IL

Average snowfall days in May - Harrisburg, IL
  • Average snowfall days in May: 0 days

The month with the highest number of snowfall days is January (5.3 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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Average daylight in May /
Average sunshine in May
Harrisburg, IL

Average daylight in May / Average sunshine in May - Harrisburg, IL
  • Average daylight in May: 14h and 1min

The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).

  • Average sunshine in May: 9h and 1min

The month with the most sunshine is June (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).

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Average sunshine days in May
Harrisburg, IL

Average sunshine days in May - Harrisburg, IL
  • Average sunshine days in May: 9.9 days

The month with the most sunshine days is October (19.5 days).
The month with the least sunshine days is May (9.9 days).

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Average UV index in May
Harrisburg, IL

Average UV index in May - Harrisburg, IL
  • Average UV index in May: 6

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

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Average cloud cover in May
Harrisburg, IL

Average cloud cover in May - Harrisburg, IL
  • Average cloud cover in May: 38

The months with the most cloud cover are January and February (Cloud cover 51).
The months with the least cloud cover are June and September (Cloud cover 28).

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Average visibility in May
Harrisburg, IL

Average visibility in May - Harrisburg, IL
  • Average visibility in May: 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).

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Harrisburg, Illinois, USA

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