Collinsville · first 14 days — live forecast · rest of month — climate corridor
🗺️ 14-day forecast map
Collinsville & neighbors — hit play
Every city on the map carries real forecast data from the same models as its city page, refreshed several times a day. The icon is the day's overall look; the number is the afternoon high.
Next 14 days at a glance
from the model forecast
Hottest day
97°
Mon, Aug 31
Coldest night
62°
Sun, Aug 23
Days with precip
3 / 14
of 14 forecast days
Nicest day
Fri, Aug 28
mild, dry, light wind
The next 4 weekends
plan ahead
Sat 29 – Sun 30 Aug
85° 65°
8% precip chance
Sat 5 – Sun 6 Sep
81° 61°
typical range
Sat 12 – Sun 13 Sep
81° 60°
typical range
Sat 19 – Sun 20 Sep
81° 57°
typical range
30 days — Collinsville
14 forecast + 16 climatology
Sun · Today Mostly cloudy
84°62°9%⌄
Wind6 mph SE
Gusts17 mph
UV index7 – High
Precip chance9%
Sunrise06:21
Sunset19:43
Mon · Tomorrow Sunny
84°62°8%⌄
Wind14 mph E
Gusts25 mph
UV index9 – Very high
Precip chance8%
Sunrise06:22
Sunset19:42
Tuesday 25/8 Mostly cloudy
88°67°9%⌄
Wind9 mph SE
Gusts24 mph
UV index8 – High
Precip chance9%
Sunrise06:23
Sunset19:41
Wednesday 26/8 Sunny
90°71°1.8 mm⌄
Wind11 mph NE
Gusts23 mph
UV index3 – Moderate
Precip chance57%
Sunrise06:23
Sunset19:39
Thursday 27/8 Sunny
83°66°0.2 mm⌄
Wind15 mph N
Gusts24 mph
UV index7 – High
Precip chance17%
Sunrise06:24
Sunset19:38
Friday 28/8 Sunny
82°62°7%⌄
Wind6 mph NE
Gusts12 mph
UV index7 – High
Precip chance7%
Sunrise06:25
Sunset19:36
Saturday 29/8 Sunny
85°65°8%⌄
Wind11 mph SE
Gusts20 mph
UV index7 – High
Precip chance8%
Sunrise06:26
Sunset19:35
Sunday 30/8 Sunny
85°66°8%⌄
Wind13 mph SE
Gusts21 mph
UV index7 – High
Precip chance8%
Sunrise06:27
Sunset19:33
Monday 31/8 Showers
97°69°52.6 mm⌄
Wind15 mph S
Gusts29 mph
UV index9 – Very high
Precip chance85%
Sunrise06:28
Sunset19:32
Tuesday 1/9 Sunny
87°69°6.7 mm⌄
Wind14 mph SW
Gusts34 mph
UV index8 – Very high
Precip chance72%
Sunrise06:29
Sunset19:30
Wednesday 2/9 Sunny
90°71°8%⌄
Wind7 mph N
Gusts16 mph
UV index8 – Very high
Precip chance8%
Sunrise06:30
Sunset19:29
Thursday 3/9 Sunny
83°66°0.6 mm⌄
Wind11 mph NE
Gusts24 mph
UV index7 – High
Precip chance36%
Sunrise06:30
Sunset19:27
Friday 4/9 Mostly cloudy
80°64°13%⌄
Wind10 mph E
Gusts22 mph
UV index6 – High
Precip chance13%
Sunrise06:31
Sunset19:26
Saturday 5/9 Mostly cloudy
81°63°8%⌄
Wind9 mph E
Gusts23 mph
UV index7 – High
Precip chance8%
Sunrise06:32
Sunset19:24
Sunday 6/9 Rain (climatological)
80°61°12.5 mm⌄
Day≈75–85°
Night≈55–66°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Monday 7/9 Partly cloudy (climatological)
83°63°20%⌄
Day≈78–89°
Night≈57–68°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Tuesday 8/9 Partly cloudy (climatological)
85°64°20%⌄
Day≈80–91°
Night≈59–69°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Wednesday 9/9 Rain (climatological)
82°62°7.6 mm⌄
Day≈76–87°
Night≈56–67°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Thursday 10/9 Partly cloudy (climatological)
79°60°20%⌄
Day≈74–84°
Night≈55–65°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Friday 11/9 Partly cloudy (climatological)
74°57°20%⌄
Day≈69–80°
Night≈52–63°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Saturday 12/9 Rain (climatological)
78°60°17.0 mm⌄
Day≈73–83°
Night≈54–65°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Sunday 13/9 Partly cloudy (climatological)
81°61°20%⌄
Day≈76–86°
Night≈56–67°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Monday 14/9 Partly cloudy (climatological)
84°63°20%⌄
Day≈78–89°
Night≈58–68°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Tuesday 15/9 Rain (climatological)
86°64°15.6 mm⌄
Day≈81–91°
Night≈59–70°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Wednesday 16/9 Partly cloudy (climatological)
80°61°20%⌄
Day≈74–85°
Night≈55–66°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Thursday 17/9 Partly cloudy (climatological)
75°58°20%⌄
Day≈69–80°
Night≈52–63°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Friday 18/9 Rain (climatological)
72°56°8.0 mm⌄
Day≈67–78°
Night≈51–61°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Saturday 19/9 Partly cloudy (climatological)
73°57°20%⌄
Day≈68–79°
Night≈51–62°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Sunday 20/9 Partly cloudy (climatological)
81°62°20%⌄
Day≈76–87°
Night≈56–67°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
Monday 21/9 Rain (climatological)
85°64°14.7 mm⌄
Day≈80–90°
Night≈58–69°
Precip≈5.3 in / September
(climatological)Typical range for these dates · 1991–2020
How does a 30-day outlook work?
The first 14 days are a live model forecast. The back half of the month shows the typical range for those dates — useful for planning, not a literal prediction.
First 14 days: a real forecast, blended from NBM, ECMWF and GFS runs. Trust it most inside three days; by the second week treat it as a lean, not a promise.
Rest of the month: past day 14 we stop pretending to forecast and switch to the climate corridor — the range those dates have produced over three decades computed directly for Collinsville, with mild week-to-week wiggle.
Good question for this page: "Is late August usually humid in Chicago?" Bad question: "Do I need an umbrella on the 29th?" — three weeks out no one knows, and that's the honest answer.