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Shaded-relief map of South Wilmington, Illinois: rivers, roads, the city limits and where the water drains.
ILLINOIS · GRUNDY COUNTY

South Wilmington

715 people, 590 ft above sea level in Grundy County.

590 ftElevation, city center
715People, 2024 estimate
0 sq miLand area
Sunny 47°
Sunny now Dew point 29° · NNW 12 mph · high 44°
City of South Wilmington River Interstate 2 miles
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The South Wilmington plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.

MILE1
TODAY

Today in South Wilmington

NWS forecast and National Blend of Models · updated 2:00 PM CST
RIGHT NOW Greater Kankakee Airport (KIKK) · 2:35 PM
Sunny
47° Sunny Feels like 42° · high of 44° near 2 PM
WindNNW 12 mphno gusts
Humidity49%falling to 51% this afternoon
Pressure30.26 in →steady
Visibility10 mihaze-free
CloudsClear
UV index—no forecast
Dew point 29° · Dryabout the same for three days
DryComfortableStickyMuggyOppressive
NEXT RAIN
Clear
Not this weeknone in the forecast for a week
LIKELY AMOUNT—nothing expected
LAST RAINNov. 130.02 in · 1 dry day
ALERTS & OUTLOOKS
No watches or warnings for Grundy County
NWS Chicago and the Storm Prediction Center · checked 2:46 PM
SUN & MOON
↑ 6:39 AM4:35 PM ↓
9 h 55 m of daylight, 2 minutes less than yesterday
Waxing crescent, 25% lit. Next full moon: Nov. 24.
AIR & POLLEN
9
GOODAir quality index · fine particles
Tomorrow: None, moderate. No pollen source yet.

The next three days, hour by hour

Sky: clear, cloudy, night Rain likely National Blend of Models
SATURDAY, NOV. 14
SUNDAY, NOV. 15
MONDAY, NOV. 16
TUESDAY, NOV. 17
2p
5p
8p
11p
2a
5a
8a
11a
2p
5p
8p
11p
2a
5a
8a
11a
2p
5p
8p
11p
2a
5a
8a
11a
clear day
clear night
clear night
clear night
mostly clear night
mostly clear night
mostly sunny
clear day
clear day
clear night
mostly clear night
mostly clear night
mostly clear night
partly cloudy night
clear day
clear day
clear day
mostly clear night
mostly clear night
clear night
mostly clear night
mostly clear night
mostly sunny
clear day
TEMPERATURE °F
44°
26°
48°
26°
50°
29°
CHANCE OF RAIN
50%
WIND, MPH
9
5
2
0
2
0
0
0
0
0
0
0
0
0
0
6
5
2
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3
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8
HOW IT FEELS · DEW POINT
Dry: dew points 26 to 34°

The next seven days, and how sure we are

Forecast, with the range 8 in 10 ensemble members agree on Normal, about 50° / 33°
SAT Nov. 14 Sunny Sunny
44° 25°
0% rain — NW 8 A
SUN Nov. 15 Mostly sunny; warmer Mostly sunny; warmer
52° 25°
0% rain — NW 0 A
MON Nov. 16 Sunny Sunny
55° 29°
0% rain — SW 3 A
TUE Nov. 17 Sunny Sunny
57° 32°
0% rain — S 6 A
WED Nov. 18 Partly cloudy Partly cloudy
60° 41°
0% rain — S 10 A
THU Nov. 19 Partly cloudy Partly cloudy
63° 43°
10% rain — SW 7 B
FRI Nov. 20 Partly cloudy Partly cloudy
64° 46°
10% rain — SSE 7 C
How sure are we? AModels agree: highs within 4° BSome spread: within 8° CWide spread: check back
Range from the National Blend of Models percentiles · graded on Forecast Scores
AIR MAIL

Where today’s air came from

The air arriving over South Wilmington about 5,000 feet above the ground was over the open Pacific three days ago, and over the northern Plains a day ago, about 2,760 miles back along its path. It came down from about 11,400 feet up, warming and drying as it sank. Near the ground the air came from the Canadian Prairies; at 10,000 feet, from British Columbia. It feels dry all the same. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.

THIS WEEK, FOUR YEARS AGO Nov. 11, 2022

The hottest this week has been

75° on Nov. 11, 2022, the hottest reading for this week of the year since 1990. Next is 74° in 1999.

74°
75°
19992022
Source: NOAA RCC-ACIS, the Dwight Wwtp record since 1990.
MILE2
THE GROUND

What South Wilmington stands on

South Wilmington’s center stands about 590 ft above sea level. Within three miles the land runs from 570 ft to 610 ft, a difference of 40 ft: nearly flat ground.

Under the town center the state geologic map shows Carbondale Formation (shale, sandstone, coal), from the Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old.

The section below crosses 2 rock units mapped at the surface.

South Wilmington, cut in half from south to north

A section south to north, 24 miles through the town center
500 ft600 ft SOUTH WILMINGTON590 ftHigh point of the line680 ftMazon Riverabout 560 ftLow point500 ft ← S · CaberyN →

Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.

Rock at the surface along the line

Carbondale Formation

Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 22 mi of the line.

Tradewater Formation

Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 2 mi of the line.

From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.

Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.

MILE3
THE WATER

Where South Wilmington’s rain goes

A raindrop that lands in South Wilmington reaches the Gulf of America by way of Gooseberry Creek, the Mazon, the Illinois and the Mississippi: about 1,480 river miles.

THE WAY DOWN, TO SCALE
South Wilmington≈ 1,480 mi · the Gulf of America
FROM THE CENTER OF SOUTH WILMINGTON ≈ 1,480 mi to the Gulf of America Gooseberry Creek → Mazon → Illinois → Mississippi

Lake on the way: Peoria Lake.

1,190 miles of the trip are on the Mississippi.

Traced down the USGS NHDPlus V2.1 river network from the Census center point of South Wilmington; river miles along the main stem, rounded.

MILE5
THE ALMANAC

South Wilmington’s year

1991–2020 normals · records since 1990 · Dwight Wwtp, 8 mi southwest

South Wilmington has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 14° in January. A normal year brings about 23 inches of snow; with the rain, that comes to about 38 inches of water.

31°14°35°17°47°27°61°37°72°49°81°59°84°62°82°59°77°51°64°40°49°29°36°20° JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 1234 TODAY 37.7 in rain and snowmelt
Normal high to low, by month Record high to low, by day Rain by month Freezing
July, average84° / 62°high / low, the warmest month
January, average31° / 14°high / low, the coldest month
Rain and melted snow37.7 inwettest months: May and June
Snow a year23.3 insnowiest: January
Hottest on record103°FJuly 14, 1995
Coldest on record−22°FJanuary 31, 2019
Wettest day on record6.10 inAugust 22, 2014
Snowiest day on record16.0 inFebruary 2, 2011
90° days a year16very few reach 100°
Nights at or below 32°140and 46 days that stay below freezing
Climate typeHot-summer humid continentalKöppen Dfa

AROUND THE RING

1Freeze seasonfrom the first fall freeze, about Oct. 12, to the last in spring, about April 24 (median dates)
2Highs below freezingDec. 29 to Feb. 7; normal highs stay below 32°
3Lows below freezingNov. 8 to April 4; normal lows fall below 32°
4Wettest stretchMay through July: 13.3 of the year’s 37.7 inches
NOVEMBER 14 IN THE RECORD

On November 14 South Wilmington normally reaches 49° and falls to 30°. The record high is 74°, in 1999; the record low 8°, in 1996. The most rain on this date, 0.80 in, fell in 1991.

MONTH BY MONTH
JanFebMarAprMayJunJulAugSepOctNovDec
Normal high31°35°47°61°72°81°84°82°77°64°49°36°
Normal low14°17°27°37°49°59°62°59°51°40°29°20°
Rain and melt, in1.961.642.553.544.854.603.903.683.253.192.581.95
Snow, inches7.94.93.50.60.00.00.00.00.00.00.85.6
Record high66° (2005)73° (2024)84° (2012)89° (2002)96° (2018)99° (1994)103° (1995)100° (1991)100° (2000)89° (2025)80° (2000)69° (2012)
Record low−22° (2019)−19° (2014)−5° (2015)14° (2018)24° (2005)30° (1993)43° (2001)41° (2002)27° (1995)20° (1992)4° (2019)−13° (2000)

Normals 1991–2020 and records since 1990 at Dwight Wwtp, 8 miles southwest. NOAA, through RCC-ACIS.

MILE7
ON THE NETWORK

Around South Wilmington on the Forecast Network

Neighboring plates

Joliet IL · 25 MI 25 miles north Bolingbrook IL · 37 MI 37 miles north Chicago IL · 55 MI 55 miles northeast Milwaukee WI · 131 MI 131 miles north Madison WI · 145 MI 145 miles northwest Indianapolis IN · 148 MI 148 miles southeast
FORECASTCITY
Map of South Wilmington, Illinois. Explore the plate
ILLINOIS · GRUNDY

South Wilmington

715 people, 590 ft above sea level in Grundy County.

590 ftElevation
715People
0 sq miLand
Sunny 47°
SunnyDew point 29°
1

Today in South Wilmington

NEXT 15 HOURS
Now clear day 44° 0%
5p clear night 39° 0%
8p clear night 33° 0%
11p clear night 29° 0%
2a mostly clear night 27° 0%
5a mostly clear night 26° 0%
Clear
NEXT RAINNone this week
→
Sat0%
Sunny Sunny
25
44
A
Sun0%
Mostly sunny; warmer Mostly sunny; warmer
25
52
A
Mon0%
Sunny Sunny
29
55
A
Tue0%
Sunny Sunny
32
57
A
Wed0%
Partly cloudy Partly cloudy
41
60
A
Thu10%
Partly cloudy Partly cloudy
43
63
B
Fri10%
Partly cloudy Partly cloudy
46
64
C
Letters show how sure the forecast is: A, models agree; B, some spread; C, check back. Sample data.
THIS WEEK, FOUR YEARS AGO · NOV. 11, 2022

75°, the hottest this week of the year has been since 1990.

2

What South Wilmington stands on

South Wilmington’s center stands about 590 ft above sea level. Within three miles the land runs from 570 ft to 610 ft, a difference of 40 ft: nearly flat ground.

South Wilmington, south to north South Wilmington590 ftHigh point680 ftMazon Riverabout 560 ft ← SN → 24 miles through the town center; vertical exaggeration about 122×. Colors: rock at the surface.
Elevation, center590 ft
Within 3 miles570 to 610 ft
Lie of the landNearly flat (40 ft of relief)
Rock at the surfaceCarbondale Formation
Its ageMiddle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old
5

South Wilmington’s year

South Wilmington has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 14° in January. A normal year brings about 23 inches of snow; with the rain, that comes to about 38 inches of water.

JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 1234 37.7 in
July, average84° / 62° · high / low, the warmest month
January, average31° / 14° · high / low, the coldest month
Rain and melted snow37.7 in · wettest months: May and June
Snow a year23.3 in · snowiest: January
Hottest on record103°F · July 14, 1995
Coldest on record−22°F · January 31, 2019
Wettest day on record6.10 in · August 22, 2014
Snowiest day on record16.0 in · February 2, 2011
90° days a year16 · very few reach 100°
Nights at or below 32°140 · and 46 days that stay below freezing
Climate typeHot-summer humid continental · Köppen Dfa
1Freeze season · from the first fall freeze, about Oct. 12, to the last in spring, about April 24 (median dates)
2Highs below freezing · Dec. 29 to Feb. 7; normal highs stay below 32°
3Lows below freezing · Nov. 8 to April 4; normal lows fall below 32°
4Wettest stretch · May through July: 13.3 of the year’s 37.7 inches
NOVEMBER 14 IN THE RECORD

On November 14 South Wilmington normally reaches 49° and falls to 30°. The record high is 74°, in 1999; the record low 8°, in 1996. The most rain on this date, 0.80 in, fell in 1991.

Normals 1991–2020 and records since 1990 at Dwight Wwtp, 8 miles southwest. NOAA, through RCC-ACIS.
3

Where the rain goes

≈ 1,480 mito the Gulf of AmericaGooseberry Creek → Mazon → Illinois → Mississippi

A raindrop that lands in South Wilmington reaches the Gulf of America by way of Gooseberry Creek, the Mazon, the Illinois and the Mississippi: about 1,480 river miles.

Lake on the way: Peoria Lake.

1,190 miles of the trip are on the Mississippi.