Summit has chilly, snowy winters and warm summers. A typical July afternoon reaches 84°, a January night drops to 17°, and about 39 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
17°
1436th mildest of 2,886 Illinois towns
💧
Rain + melted snow
38 in
960th driest of 2,886 Illinois towns
🌨️
Snow a winter
39 in
122nd snowiest of 2,880 Illinois towns
A normal year
What a year in Summit feels like
❄️
Winter
35° / 20°
Typical high / low · 11 days with an inch or more of snow
🌷
Spring
59° / 39°
Typical high / low · Last frost around Apr 10
☀️
Summer
82° / 62°
Typical high / low · 21 days reach 90° in a normal year
🍂
Fall
63° / 44°
Typical high / low · First frost around Nov 1
0°
10°
20°
40°
50°
60°
70°
80°
90°
100°
32°
32°
17°
36°
20°
47°
29°
60°
39°
71°
50°
81°
59°
84°
65°
82°
63°
76°
55°
63°
44°
49°
33°
37°
23°
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
Summit 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
32°
17°
2.0"
12.5"
12
18
16° – 36°
February
36°
20°
1.8"
10.1"
9
12
16° – 39°
March
47°
29°
2.4"
5.7"
11
4
31° – 53°
April
60°
39°
3.9"
1.0"
12
1
41° – 55°
May
71°
50°
4.5"
0
12
0
54° – 67°
June
81°
59°
4.3"
0
11
0
66° – 75°
July
84°
65°
3.7"
0
10
0
69° – 81°
August
82°
63°
4.2"
0
9
0
68° – 79°
September
76°
55°
3.3"
0
8
0
60° – 70°
October
63°
44°
3.6"
0.1"
11
0
49° – 59°
November
49°
33°
2.6"
1.5"
10
1
33° – 49°
December
37°
23°
2.1"
7.9"
11
9
17° – 40°
Year
60°
41°
38.4"
38.8"
127
44
“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 Summit
Summit 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 127 days a year. Snow covers the ground about 44 days of the year.
💧
38 in
Rain + melted snow a year
Less rain than 55% of U.S. towns
❄️
39 in
Snow in a normal winter
More snow than 68% of U.S. towns
⛄
44 days
With 1"+ of snow on the ground
More than 62% of U.S. towns
Rain + melted snow by month
Inches of water
4.5"
JFMAMJJASOND
Snowfall by month
Inches of snow
13"
JFMAMJJASOND
Frost & the growing season
About 203 frost-free days a year
In half of years the last 32° night comes by April 10 and the first one by November 1. That leaves about 203 frost-free days for gardens, longer than 74% of U.S. towns.
🌱 Apr 10
🍂 Nov 1
203 frost-free days
JFMAMJJASOND
🥶
108
nights at or below 32° in a normal year
🧊
4
nights below 0° in a normal year
🔥
21
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 Summit
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Summit, 83% of that work is heating and 17% is cooling, so the furnace matters far more than the air conditioner.
🔥
5,699 heating degree daysLess heating than 51% of U.S. towns
❄️
1,161 cooling degree daysMore cooling than 68% 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 Summit
Summit and its neighbors
Summit borders 7 towns with climate data. January nights across them vary by 1.2°. Lyons has both the coldest January nights (17°) and the hottest July afternoons (84°). Summit’s January low is 17° 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 Summit averaged 1.4° warmer than the 1900s. The biggest change is in December (+2.6°). The shift is larger than in 63% of U.S. towns.
❄️ Winter+2.2°now 28°, was 25°
🌷 Spring+1.4°now 49°, was 48°
☀️ Summer+0.9°now 72°, was 71°
🍂 Fall+1.1°now 53°, was 52°
Change by month1991–2020 average minus 1901–2000 average, at Summit’s spot on NOAA’s grid
+0.5°
+2.6°
JanJFebFMarMAprAMayMJunJJulJAugASepSOctONovNDecD
Year to year
How much a month can swing
A normal is an average, and real years wander around it. December swings the most: between 1991 and 2020 its average temperature ranged from 17° to 40°. 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 Summit’s climate
What is the coldest month in Summit?
January, with a typical high of 32° and a low of 17°.
What is the hottest month in Summit?
July, with a typical high of 84° and a low of 65°. About 21 days a year reach 90°.
How much snow does Summit get?
About 39 inches in a normal winter, most of it in January.
When is the first frost in Summit?
In half of years the first 32° night comes by November 1, and the last spring frost by April 10.
What is the rainiest month in Summit?
May, with 4.5 inches of rain and melted snow. The year totals 38 inches.
📍Temperatures and rainfall come from NOAA’s gridded climate normals for Summit itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Chicago Midway Airport 3sw, IL (4 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.