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Williamson County (Energy)
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United States weather

Weather in Williamson County, Illinois for May 2026

Your guide to Williamson County weather in May - trends and predictions

    Official Weather Alert ⚠️

  • Flood Warning - See hour by hour.

    • Temperatures

  • The forecast for the upcoming days in Williamson County predicts a temperature of 23.1 °F, which is slightly above the historical average.

  • In general, the average temperature in Williamson County at the beginning of May is 19.3 °F. As the month progressed, temperatures tended to significantly warm up, reaching an average of 22.9 °F by the end of May.

    • Rain 🌧️

  • Williamson County experiences heavy rainfall in May, with over 20 rainy days and an average total precipitation 344.8 mm.

    • More

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
5
Dry days
Average rainy days
26
Rainy days
Average snowy days
0
Snow days
Average temperatures
23°/15°
Temperatures
Average wind speed
20 km/h
Avg max wind
Average humidity
80 %
Avg humidity

Williamson County Weather May

Move between months or click on a day
April
June
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Thundery outbreaks possible
23°
2
Sunny
20°
3
Patchy rain possible
20°
4
Overcast
21°
5
Light rain shower
19°
6
Weather Alert Moderate rain
17°
7
Patchy rain possible
15°
8
Patchy rain possible
21°
9
Sunny
24°
10
Moderate rain
21°
11
Sunny
21°
12
Sunny
27°
13
Patchy rain possible
30°
14
Partly cloudy
29°
15
Patchy rain possible
29°
16
Patchy rain possible
30°
17
Patchy rain possible
23°
18
Sunny
21°
19
Partly cloudy
16°
20
Thundery outbreaks possible
27°
21
Partly cloudy
27°
22
Moderate or heavy rain with thunder
22°
23
Light rain shower
22°
24
Moderate or heavy rain with thunder
21°
25
Thundery outbreaks possible
24°
26
Thundery outbreaks possible
22°
27
Patchy rain possible
21°
28
Sunny
23°
29
Partly cloudy
22°
30
Sunny
23°
31
Patchy light drizzle
25°

Temperatures trend during May in Williamson County

See the weather trend as well as the moving average line

May weather in Williamson County day by day

Click on a date for more information
April June
Date Weather Temperatures Rain UV More
May 1 Thundery outbreaks possible
Thundery outbreaks possible
 23° /13° 6.5 mm 7
May 2 Sunny
Sunny
 20° /12° 3.1 mm 7
May 3 Patchy rain possible
Patchy rain possible
 20° /10° 30.8 mm 6
May 4 Overcast
Overcast
 21° /12° 0.8 mm 6
May 5 Light rain shower
Light rain shower
 19° /11° 18.6 mm 4
May 6 Moderate rain
Moderate rain
 17° /8° 10.8 mm 3.7
May 7 Patchy rain possible
Patchy rain possible
 15° /9° 0.2 mm 7.4
May 8 Patchy rain possible
Patchy rain possible
 21° /7° 2.1 mm 0.2
May 9 Sunny
Sunny
 24° /10° 0 mm 5
May 10 Moderate rain
Moderate rain
 21° /12° 5.5 mm 4
May 11 Sunny
Sunny
 21° /8° 0 mm 4
May 12 Sunny
Sunny
 27° /11° 0 mm 5
May 13 Patchy rain possible
Patchy rain possible
 30° /16° 0.9 mm 5
May 14 Partly cloudy
Partly cloudy
 29° /21° 0 mm 6
May 15 Patchy rain possible
Patchy rain possible
 29° /24° 0.3 mm 6
May 16 Patchy rain possible
Patchy rain possible
 30° /20° 2 mm 5
May 17 Patchy rain possible
Patchy rain possible
 23° /17° 1.2 mm 5
May 18 Sunny
Sunny
 21° /13° 0 mm 5
May 19 Partly cloudy
Partly cloudy
 16° /12° 0 mm 4
May 20 Thundery outbreaks possible
Thundery outbreaks possible
 27° /18° 52.1 mm 6
May 21 Partly cloudy
Partly cloudy
 27° /15° 5.8 mm 7
May 22 Moderate or heavy rain with thunder
Moderate or heavy rain with thunder
 22° /15° 8.2 mm 5
May 23 Light rain shower
Light rain shower
 22° /12° 1.4 mm 5
May 24 Moderate or heavy rain with thunder
Moderate or heavy rain with thunder
 21° /15° 40.8 mm 5
May 25 Thundery outbreaks possible
Thundery outbreaks possible
 24° /16° 1.9 mm 6
May 26 Thundery outbreaks possible
Thundery outbreaks possible
 22° /15° 43.1 mm 5
May 27 Patchy rain possible
Patchy rain possible
 21° /15° 23.4 mm 5
May 28 Sunny
Sunny
 23° /16° 0 mm 6
May 29 Partly cloudy
Partly cloudy
 22° /13° 0 mm 6
May 30 Sunny
Sunny
 23° /12° 3.4 mm 6
May 31 Patchy light drizzle
Patchy light drizzle
 25° /14° 2.3 mm 6
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Important Notice
Our weather forecast for Williamson County in May is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Williamson County forecast closer to your planned date for the most up-to-date weather information.
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Williamson County in May - FAQ

What are the expected maximum and minimum temperatures in Williamson County during May?

During May, expect a variety of temperatures with highs around 23° and lows near 15°, suitable for diverse activities and preferences.

How much rainfall should be expected in Williamson County during May?

Significant rainfall exceeding 344.8 mm is expected in Williamson County during May, occurring over more than 26 days. Preparing for wet conditions is recommended in your planning.

What are the typical wind conditions in Williamson County during May?

The average wind speed in Williamson County during May is 20 km/h, suggesting breezy to windy conditions, depending on your activities.

May rainfall patterns in Williamson County

Explore the daily rainfall trends and prepare for Williamson Countys May weather 💧
Typically, Williamson County has 26 rainy days in May with a total of 344.8 mm of rainfall.

UV exposure in Williamson County during May

Stay informed about UV levels for safe outdoor activities throughout the month of May ☀️
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Location coordinates Where is Williamson County?

Get accurate weather forecasts for Williamson County, located at latitude 37.774 and longitude -89.026. Stay updated with localized weather information tailored for Williamson County.

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