Climate Insights for Hainesville

Sweet Grass County, Illinois, United States

Hottest
August
25°C peak
Coldest
January
-5°C low
Wettest
May
156mm rain
Best to Visit
June, July, August
Mild temps & low rain

Climate Overview

The climate in Hainesville is cool. The average annual temperature is 9°C and approximately 1174mm of precipitation falls per year. Hainesville receives a notable amount of rainfall throughout the year, including during its driest month. Hainesville is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, September. The coldest months are January, February, December, when temperatures can drop to -5°C. Snowfall occurs from January to December, with around 119cm accumulating over the season.

Temperature

-10° 10° 20° 30° Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Max: 0° Average: -3° Min: -5° Feb Max: 2° Average: -1° Min: -3° Mar Max: 5° Average: 2° Min: 0° Apr Max: 9° Average: 5° Min: 3° May Max: 14° Average: 11° Min: 8° Jun Max: 20° Average: 17° Min: 15° Jul Max: 25° Average: 22° Min: 20° Aug Max: 25° Average: 22° Min: 20° Sep Max: 22° Average: 19° Min: 17° Oct Max: 15° Average: 12° Min: 10° Nov Max: 8° Average: 5° Min: 3° Dec Max: 2° Average: 0° Min: -2°
Max
Average
Min

Temperatures in Hainesville vary considerably across the year, with a 30°C difference between the coldest and warmest months. August is the warmest month, though highs remain moderate at 25°C with a mean of 22°C. The coldest month is January, when overnight lows fall to -5°C and the daily average is -3°C. Daily temperature variation is modest, with an average difference of 5°C between highs and lows. The sharpest temperature change occurs between September and October, with a 7°C shift in average temperatures.

Precipitation

0mm 50mm 100mm 150mm 200mm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Precipitation: 85mm Snow: 32mm Feb Precipitation: 74mm Snow: 27mm Mar Precipitation: 98mm Snow: 12mm Apr Precipitation: 141mm Snow: 14mm May Precipitation: 156mm Snow: 0mm Jun Precipitation: 93mm Snow: 0mm Jul Precipitation: 77mm Snow: 0mm Aug Precipitation: 82mm Snow: 0mm Sep Precipitation: 93mm Snow: 0mm Oct Precipitation: 139mm Snow: 2mm Nov Precipitation: 72mm Snow: 11mm Dec Precipitation: 63mm Snow: 21mm
Precipitation
Snow

Hainesville is a moderately rainy area, receiving approximately 1174mm of precipitation annually, which averages out to around 98mm per month. The wettest month is May, averaging 156mm of rainfall. April and October also tend to see above-average precipitation. The driest month is December, with just 63mm. That's 93mm less than May, the wettest month. Rainfall is relatively evenly distributed throughout the year, so there is no pronounced dry or wet season to plan around. Snowfall is a regular feature from January to December, with around 119cm accumulating over the season. January typically sees the most snow at around 32cm.

Wind

0km/h 5km/h 10km/h Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Wind Speed: 6km/h Feb Wind Speed: 6km/h Mar Wind Speed: 5km/h Apr Wind Speed: 5km/h May Wind Speed: 4km/h Jun Wind Speed: 4km/h Jul Wind Speed: 4km/h Aug Wind Speed: 4km/h Sep Wind Speed: 5km/h Oct Wind Speed: 6km/h Nov Wind Speed: 6km/h Dec Wind Speed: 6km/h
Wind Speed

Hainesville is relatively calm, with an average annual wind speed of 5km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is January, averaging 6km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 4km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 2km/h gap between the calmest and windiest months.

Seasons

Winter
Dec 21
Spring
Mar 20
Summer
Jun 21
Autumn
Sep 23

7 days until Summer

It is currently spring in Hainesville, which began on March 20, 2026. Hainesville is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 25°C, while the coldest stretch bottoms out in January near -5°C. Summer is next, beginning on June 21, 2026 — 7 days from now.

Spring

Temperatures range from 0 to 14°C. Rainfall is heavy, totalling around 396mm across the season with a monthly average of 132mm. Winds are generally light, averaging 5km/h. An umbrella or waterproof jacket is advisable as spring showers are frequent.

Summer

Temperatures range from 15 to 25°C. Precipitation is moderate at around 251mm for the season, averaging 84mm per month. Winds are generally light, averaging 4km/h. Light, breathable clothing is ideal — perfect conditions for outdoor activities.

Autumn

Temperatures range from 3 to 22°C. Rainfall is heavy, totalling around 304mm across the season with a monthly average of 101mm. Expect around 13cm of snow accumulation during this period. Winds are generally light, averaging 5km/h. A waterproof jacket and sturdy footwear are recommended as rain becomes more frequent.

Winter

Temperatures range from -5 to 2°C. Precipitation is moderate at around 223mm for the season, averaging 74mm per month. Expect around 80cm of snow accumulation during this period. Winds are generally light, averaging 6km/h. Warm winter clothing and waterproof boots are a must, and travel may be affected by snow.

Best Time to Visit

Jan -3°
Feb -1°
Mar
Apr
May 11°
Jun 17°
Jul 22°
Aug 22°
Sep 19°
Oct 12°
Nov
Dec

The best time to visit Hainesville is during June, July, August and September, when the weather is most comfortable for travellers. During these months, average temperatures hover around 20°C with modest rainfall averaging 86mm per month. By contrast, January can be quite cold with temperatures dropping to -5°C. Despite being the best months overall, some rain is still likely — pack a waterproof layer and plan a mix of indoor and outdoor activities.

Monthly Climate Data

The table below shows monthly climate averages for Hainesville based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.

Month
Min Temperature
Max Temperature
Wind Speed
Precipitation
Snow
Jan
-5 °C
0 °C
6 km/h
85 mm
32 cm
Feb
-3 °C
2 °C
6 km/h
74 mm
27 cm
Mar
0 °C
5 °C
5 km/h
98 mm
12 cm
Apr
3 °C
9 °C
5 km/h
141 mm
14 cm
May
8 °C
14 °C
4 km/h
156 mm
0 cm
Jun Current
15 °C
20 °C
4 km/h
93 mm
0 cm
Jul
20 °C
25 °C
4 km/h
77 mm
0 cm
Aug
20 °C
25 °C
4 km/h
82 mm
0 cm
Sep
17 °C
22 °C
5 km/h
93 mm
0 cm
Oct
10 °C
15 °C
6 km/h
139 mm
2 cm
Nov
3 °C
8 °C
6 km/h
72 mm
11 cm
Dec
-2 °C
2 °C
6 km/h
63 mm
21 cm
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