Oak Brook has chilly, snowy winters and warm summers. A typical July afternoon reaches 84°, a January night drops to 16°, and about 42 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normalsUpdated once a decade
☀️
July high
84°
669th coolest of 2,886 Illinois towns
❄️
January low
16°
1036th coldest of 2,886 Illinois towns
💧
Rain + melted snow
38 in
939th driest of 2,886 Illinois towns
🌨️
Snow a winter
42 in
54th snowiest of 2,880 Illinois towns
A normal year
What a year in Oak Brook feels like
❄️
Winter
34° / 19°
Typical high / low · 12 days with an inch or more of snow
🌷
Spring
59° / 39°
Typical high / low · Last frost around Apr 27
☀️
Summer
82° / 62°
Typical high / low · 29 days reach 90° in a normal year
🍂
Fall
62° / 43°
Typical high / low · First frost around Oct 17
0°
10°
20°
40°
50°
60°
70°
80°
90°
100°
32°
31°
16°
36°
20°
47°
29°
60°
38°
71°
49°
81°
59°
84°
64°
82°
62°
76°
55°
63°
43°
48°
32°
36°
22°
JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD
32°, freezingBar runs from the typical overnight low up to the afternoon high
Best months to be outsideMayJunAugSepOctHighs of 62–84° and lows of 40° or more
Month by month
Oak Brook weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
Month
High
Low
Rain + melt
Snow
Wet days
Snow on ground
30-yr range
January
31°
16°
2.0"
12.6"
11
17
15° – 35°
February
36°
20°
1.8"
14.5"
10
18
15° – 38°
March
47°
29°
2.4"
4.1"
12
6
30° – 53°
April
60°
38°
3.9"
0.8"
12
1
41° – 55°
May
71°
49°
4.7"
0
13
0
54° – 66°
June
81°
59°
4.4"
0
13
0
66° – 74°
July
84°
64°
3.8"
0
10
0
69° – 80°
August
82°
62°
4.0"
0
10
0
67° – 79°
September
76°
55°
3.3"
0
9
0
59° – 69°
October
63°
43°
3.5"
0
11
0
48° – 59°
November
48°
32°
2.5"
0.6"
9
0
32° – 48°
December
36°
22°
2.1"
9.7"
13
14
16° – 39°
Year
60°
41°
38.3"
42.3"
133
55
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain & snow
Rain and snow in Oak Brook
Oak Brook gets 38 inches of rain and melted snow a year. May is the wettest month and February the driest. Rain or snow falls on about 133 days a year. Snow covers the ground about 55 days of the year.
💧
38 in
Rain + melted snow a year
Less rain than 55% of U.S. towns
❄️
42 in
Snow in a normal winter
More snow than 73% of U.S. towns
⛄
55 days
With 1"+ of snow on the ground
More than 68% of U.S. towns
Rain + melted snow by month
Inches of water
4.7"
JFMAMJJASOND
Snowfall by month
Inches of snow
15"
JFMAMJJASOND
Frost & the growing season
About 173 frost-free days a year
In half of years the last 32° night comes by April 27 and the first one by October 17. That leaves about 173 frost-free days for gardens, shorter than 57% of U.S. towns.
🌱 Apr 27
🍂 Oct 17
173 frost-free days
JFMAMJJASOND
🥶
128
nights at or below 32° in a normal year
🧊
7
nights below 0° in a normal year
🔥
29
days that reach 90° in a normal year
Freezing nights by month
Average nights at or below 32°
JFMAMJJASOND
90° days by month
Average days at 90° or more
JFMAMJJASOND
Heating & cooling
Heating and cooling a home in Oak Brook
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Oak Brook, 86% of that work is heating and 14% is cooling, so the furnace matters far more than the air conditioner.
🔥
5,976 heating degree daysMore heating than 55% of U.S. towns
❄️
938 cooling degree daysMore cooling than 57% of U.S. towns
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Around Oak Brook
Oak Brook and its neighbors
Oak Brook borders 9 towns with climate data. January nights across them vary by 1.2°. Lombard has the coldest January nights (16°) and Proviso the hottest July afternoons (84°). Oak Brook’s January low is 16° and its July high 84°.
Compared with every U.S. town and city on TownTapestry, each counted once.
Then and now
Warmer than it used to be
+1.4°1991–2020 average vs. the 20th century (1901–2000)
The last 30 years in Oak Brook averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.7°). The shift is larger than in 67% of U.S. towns.
❄️ Winter+2.2°now 27°, was 25°
🌷 Spring+1.4°now 49°, was 47°
☀️ Summer+1.0°now 72°, was 71°
🍂 Fall+1.1°now 53°, was 52°
Change by month1991–2020 average minus 1901–2000 average, at Oak Brook’s spot on NOAA’s grid
+0.5°
+2.7°
JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD
Year to year
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 15° to 38°. June is the most reliable, staying within 9°.
10°
20°
30°
40°
50°
60°
70°
80°
90°
JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD
Coldest to warmest month in 30 yearsNormal
Questions
Common questions about Oak Brook’s climate
What is the coldest month in Oak Brook?
January, with a typical high of 31° and a low of 16°.
What is the hottest month in Oak Brook?
July, with a typical high of 84° and a low of 64°. About 29 days a year reach 90°.
How much snow does Oak Brook get?
About 42 inches in a normal winter, most of it in February.
When is the first frost in Oak Brook?
In half of years the first 32° night comes by October 17, and the last spring frost by April 27.
What is the rainiest month in Oak Brook?
May, with 4.7 inches of rain and melted snow. The year totals 38 inches.
📍Temperatures and rainfall come from NOAA’s gridded climate normals for Oak Brook itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Oak Brook 2w, IL (1 mi, snow) and Wheaton 3 Se, IL (6 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.