Monthly climate in Olney, Illinois, United States

Last updated: May 6, 2024

Under the Köppen–Geiger climate classification Olney features a humid subtropical climate (Cfa).Temperatures typically range between 1 °C (33 °F) and 26 °C (80 °F) through the year, but rarely can drop to -20 °C (-4 °F) or can rise to as high as 37 °C (98 °F).The average annual precipitation amounts to about 1256 mm (49.5 inches) and receives 120 rainy days on the 1 mm (0.04 inches) threshold annually.Olney enjoys an average of 2959 hours of sunshine throughout the year, and daylight varies from 9 hours 29 minutes to 14 hours 49 minutes per day.

Monthly average temperatures in Olney, Illinois, United States §

The warmest months in Olney are June, July and August, with daily mean temperatures ranging from 25 to 26 °C (77 - 80 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from 1 to 4 °C (33 - 39 °F) throughout the day. On average each year, Olney experiences 124 days above 25 °C (77.0 °F) and 75 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Olney, Illinois, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to June 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maximum 20°C
(69°F)
23°C
(74°F)
24°C
(75°F)
30°C
(86°F)
35°C
(95°F)
36°C
(97°F)
37°C
(98°F)
35°C
(96°F)
34°C
(94°F)
34°C
(94°F)
26°C
(79°F)
20°C
(68°F)
Mean maximum 16°C
(62°F)
19°C
(67°F)
22°C
(73°F)
28°C
(83°F)
32°C
(91°F)
34°C
(94°F)
35°C
(96°F)
34°C
(93°F)
33°C
(92°F)
31°C
(89°F)
22°C
(71°F)
19°C
(66°F)
Average high 4°C
(40°F)
7°C
(45°F)
13°C
(56°F)
18°C
(65°F)
25°C
(77°F)
30°C
(86°F)
31°C
(88°F)
30°C
(85°F)
28°C
(83°F)
21°C
(70°F)
12°C
(53°F)
9°C
(48°F)
Daily mean 1°C
(33°F)
2°C
(37°F)
8°C
(47°F)
13°C
(56°F)
20°C
(68°F)
25°C
(77°F)
26°C
(80°F)
25°C
(77°F)
23°C
(73°F)
16°C
(60°F)
7°C
(44°F)
4°C
(39°F)
Average low -3°C
(27°F)
-2°C
(29°F)
3°C
(38°F)
8°C
(46°F)
15°C
(59°F)
20°C
(68°F)
22°C
(71°F)
20°C
(68°F)
17°C
(63°F)
10°C
(51°F)
2°C
(35°F)
-0°C
(32°F)
Mean minimum -15°C
(5°F)
-15°C
(6°F)
-8°C
(19°F)
-1°C
(30°F)
5°C
(42°F)
15°C
(59°F)
16°C
(61°F)
14°C
(57°F)
9°C
(48°F)
1°C
(34°F)
-7°C
(20°F)
-11°C
(13°F)
Minimum -20°C
(-4°F)
-17°C
(1°F)
-15°C
(5°F)
-3°C
(27°F)
2°C
(36°F)
11°C
(51°F)
15°C
(59°F)
13°C
(55°F)
8°C
(47°F)
-3°C
(27°F)
-12°C
(11°F)
-17°C
(1°F)

Compare climate in Olney with other places

Compare temperature, precipitation, sunshine, UV index in Olney, Illinois, United States with other places around the world.

Monthly average precipitation in Olney, Illinois, United States §

Olney usually has the most precipitation in March, April and May, with an average of 12 rainy days and 129 mm (5.1 inches) of precipitation per month.The driest months in Olney are January, September and December. On average, 83 mm (3.3 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Olney, Illinois, United States.Generated using Copernicus Climate Change Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average precipitation mm (inches) 91 (3.6) 105 (4.1) 131 (5.2) 119 (4.7) 137 (5.4) 114 (4.5) 101 (4.0) 93 (3.7) 68 (2.7) 103 (4.1) 102 (4.0) 92 (3.6)
Average precipitation days (≥ 1 mm) 9 10 13 10 14 11 11 9 6 10 9 8

Monthly sunshine hours in Olney, Illinois, United States §

The sunniest months in Olney are June, July and August, when the sun shines an average of 10 hours 57 minutes a day.Least sunny months in Olney: January, February and December receive an average of 5 hours 9 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Olney, Illinois, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2017 to January 2022.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean monthly sunshine hours 119 164 210 250 283 330 353 324 293 240 204 184
Mean daily daylight hours 9h 47m 10h 45m 11h 58m 13h 14m 14h 17m 14h 49m 14h 31m 13h 35m 12h 23m 11h 8m 10h 2m 9h 29m

Solar UV radiation in Olney, Illinois, United States §

Olney experiences the highest level of ultraviolet (UV) radiation in May, June and July, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / Extreme category of sun exposure.January, November and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly Olney UV Index data.

Average daily maximum UV levels by month for Olney, Illinois, United States.Generated using Copernicus Atmosphere Monitoring Service information.Data for period from January 2022 to January 2023.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UV Index (month maximum) 3 5 7 9 10 11 10 9 9 6 4 3