Monthly outlook for Mundelein, IL: average high 81.7°, average low 65.6°. That is 2.2° above the climate normal for August. Precipitation is expected on 5 days (about 2.4 inches), against a normal of 6 days and 1.8 inches. The warmest day looks like 22 August (93.3°), the coolest 14 August (57.9°).
81.7°/65.6°
Average high / low
+2.2°
Above normal
5 / 6
Wet days / normal
2.4 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
9 August – 18 August
78.6°
77.9°
+0.4°
19 August – 28 August
86.9°
77.8°
+5.1°
29 August – 7 September
at normal
76.1°
—
August records over 66 years
98.6°24 August 2023All-time high
52.5°22 August 2024All-time low
Climate normals and records are computed from the nearest reference point — Highwood (11 mi).
Mon, 1088° / 69°0.5
88 °
Mundelein, Monday, 10 August
Rain. High 88°, low 69°.
Pressure29.88 inHg
Wind4.2 mph N
Humidity71%
Visibility6.2 mi
Dew point72°
Tue, 1182° / 67°0.48
82 °
Mundelein, Tuesday, 11 August
Heavy rain. High 82°, low 67°.
Pressure29.83 inHg
Wind9.6 mph E
Humidity98%
Visibility3.9 mi
Dew point67°
Wed, 1282° / 68°0.03
82 °
Mundelein, Wednesday, 12 August
Light rain. High 82°, low 68°.
Pressure29.83 inHg
Wind6.4 mph NW
Humidity66%
Visibility6.2 mi
Dew point70°
Thu, 1373° / 63°0
73 °
Mundelein, Thursday, 13 August
Overcast. High 73°, low 63°.
Pressure30.03 inHg
Wind8.4 mph NE
Humidity56%
Visibility—
Dew point56°
Fri, 1473° / 58°0
73 °
Mundelein, Friday, 14 August
Mostly clear. High 73°, low 58°.
Pressure30.18 inHg
Wind9.4 mph NE
Humidity49%
Visibility—
Dew point51°
Sat, 1578° / 59°0
78 °
Mundelein, Saturday, 15 August
Overcast. High 78°, low 59°.
Pressure30.21 inHg
Wind8.2 mph E
Humidity42%
Visibility—
Dew point51°
Sun, 1672° / 65°0.03
72 °
Mundelein, Sunday, 16 August
Light rain. High 72°, low 65°.
Pressure30.09 inHg
Wind4.5 mph SE
Humidity67%
Visibility—
Dew point59°
Mon, 1779° / 64°0.04
79 °
Mundelein, Monday, 17 August
Light rain. High 79°, low 64°.
Pressure30.06 inHg
Wind9.1 mph NE
Humidity62%
Visibility—
Dew point63°
Tue, 1878° / 62°0
78 °
Mundelein, Tuesday, 18 August
Overcast. High 78°, low 62°.
Pressure30.03 inHg
Wind4.9 mph SE
Humidity70%
Visibility—
Dew point60°
Wed, 1985° / 67°0.21
85 °
Mundelein, Wednesday, 19 August
Light rain. High 85°, low 67°.
Pressure29.88 inHg
Wind14.8 mph S
Humidity56%
Visibility—
Dew point65°
Thu, 2092° / 74°0
92 °
Mundelein, Thursday, 20 August
Overcast. High 92°, low 74°.
Pressure29.77 inHg
Wind7.3 mph SE
Humidity64%
Visibility—
Dew point71°
Fri, 2183° / 69°0
83 °
Mundelein, Friday, 21 August
Clear. High 83°, low 69°.
Pressure29.94 inHg
Wind11.8 mph NE
Humidity52%
Visibility—
Dew point62°
Sat, 2293° / 67°0.01
93 °
Mundelein, Saturday, 22 August
Light rain. High 93°, low 67°.
Pressure29.85 inHg
Wind10.7 mph S
Humidity46%
Visibility—
Dew point64°
Sun, 2391° / 68°0
91 °
Mundelein, Sunday, 23 August
Overcast. High 91°, low 68°.
Pressure29.83 inHg
Wind11.6 mph NE
Humidity47%
Visibility—
Dew point65°
Mon, 2477° / 68°0.03
77 °
Mundelein, Monday, 24 August
Light rain. High 77°, low 68°.
Pressure30.06 inHg
Wind12.9 mph NE
Humidity77%
Visibility—
Dew point66°
From day 17 onward the outlook is built from 60-year climate statistics
Tue, 2578° / 68°0.07
78 °
Mundelein, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.07 in
Chance of precipitation25%
Record high91° (2024)
Record low54° (2017)
Wed, 2679° / 68°0.14
79 °
Mundelein, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.14 in
Chance of precipitation35%
Record high94° (2024)
Record low54° (2025)
Thu, 2778° / 69°0.1
78 °
Mundelein, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high78°
Average low69°
Average precipitation0.1 in
Chance of precipitation32%
Record high96° (2024)
Record low55° (2025)
Fri, 2878° / 68°0.12
78 °
Mundelein, Friday, 28 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.12 in
Chance of precipitation35%
Record high92° (2021)
Record low54° (1986)
Sat, 2978° / 68°0.13
78 °
Mundelein, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high78°
Average low68°
Average precipitation0.13 in
Chance of precipitation28%
Record high89° (1984)
Record low54° (1965)
Sun, 3077° / 67°0.09
77 °
Mundelein, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high77°
Average low67°
Average precipitation0.09 in
Chance of precipitation27%
Record high91° (2013)
Record low57° (2023)
Mon, 3176° / 67°0.06
76 °
Mundelein, Monday, 31 August
Climate normal for this date — 60-year average.
Average high76°
Average low67°
Average precipitation0.06 in
Chance of precipitation20%
Record high89° (2012)
Record low56° (2025)
Tue, 0176° / 67°0.1
76 °
Mundelein, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high76°
Average low67°
Average precipitation0.1 in
Chance of precipitation28%
Record high89° (1960)
Record low57° (2017)
Wed, 0277° / 67°0.04
77 °
Mundelein, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high77°
Average low67°
Average precipitation0.04 in
Chance of precipitation25%
Record high87° (2023)
Record low50° (2017)
Thu, 0376° / 66°0.09
76 °
Mundelein, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high76°
Average low66°
Average precipitation0.09 in
Chance of precipitation27%
Record high92° (2023)
Record low54° (1974)
Fri, 0475° / 66°0.08
75 °
Mundelein, Friday, 4 September
Climate normal for this date — 60-year average.
Average high75°
Average low66°
Average precipitation0.08 in
Chance of precipitation30%
Record high91° (2023)
Record low49° (2025)
Sat, 0575° / 65°0.08
75 °
Mundelein, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.08 in
Chance of precipitation25%
Record high89° (2023)
Record low55° (2017)
Sun, 0675° / 65°0.09
75 °
Mundelein, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.09 in
Chance of precipitation33%
Record high90° (1990)
Record low49° (2025)
Mon, 0775° / 65°0.07
75 °
Mundelein, Monday, 7 September
Climate normal for this date — 60-year average.
Average high75°
Average low65°
Average precipitation0.07 in
Chance of precipitation28%
Record high89° (1960)
Record low48° (2025)
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Mundelein, IL are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Mundelein, IL since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.