Monthly outlook for Chicago, IL: average high 79°, average low 67°. That is 0.5° below the climate normal for August. Precipitation is expected on 6 days (about 2.4 inches), against a normal of 6 days and 1.9 inches. The warmest day looks like 11 August (86.4°), the coolest 23 August (58.6°).
79°/67°
Average high / low
−0.5°
Below normal
6 / 6
Wet days / normal
2.4 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
80.6°
80.1°
+0.3°
18 August – 27 August
76.4°
79.9°
-2°
28 August – 6 September
at normal
78.5°
—
August records over 66 years
98.6°24 August 2023All-time high
49.8°29 August 1965All-time low
Sun, 0983° / 67°1.53
83 °
Chicago, Sunday, 9 August
Heavy rain. High 83°, low 67°.
Pressure29.91 inHg
Wind14.9 mph NW
Humidity90%
Visibility—
Dew point70°
Mon, 1083° / 73°0.1
83 °
Chicago, Monday, 10 August
Light rain. High 83°, low 73°.
Pressure29.88 inHg
Wind4.1 mph SE
Humidity69%
Visibility6.2 mi
Dew point69°
Tue, 1186° / 73°0.18
86 °
Chicago, Tuesday, 11 August
Rain. High 86°, low 73°.
Pressure29.80 inHg
Wind9.1 mph W
Humidity55%
Visibility6.2 mi
Dew point69°
Wed, 1285° / 70°0.02
85 °
Chicago, Wednesday, 12 August
Light rain. High 85°, low 70°.
Pressure29.85 inHg
Wind4.7 mph NE
Humidity61%
Visibility6.2 mi
Dew point64°
Thu, 1372° / 66°0.06
72 °
Chicago, Thursday, 13 August
Light rain. High 72°, low 66°.
Pressure29.94 inHg
Wind11.5 mph E
Humidity67%
Visibility—
Dew point59°
Fri, 1474° / 64°0
74 °
Chicago, Friday, 14 August
Clear. High 74°, low 64°.
Pressure30.18 inHg
Wind11 mph NE
Humidity45%
Visibility—
Dew point50°
Sat, 1579° / 62°0
79 °
Chicago, Saturday, 15 August
Overcast. High 79°, low 62°.
Pressure30.30 inHg
Wind6 mph S
Humidity37%
Visibility—
Dew point47°
Sun, 1681° / 62°0
81 °
Chicago, Sunday, 16 August
Partly cloudy. High 81°, low 62°.
Pressure30.18 inHg
Wind9.7 mph SW
Humidity42%
Visibility—
Dew point52°
Mon, 1779° / 69°0.08
79 °
Chicago, Monday, 17 August
Light rain. High 79°, low 69°.
Pressure30.00 inHg
Wind6 mph S
Humidity80%
Visibility—
Dew point66°
Tue, 1881° / 71°0
81 °
Chicago, Tuesday, 18 August
Overcast. High 81°, low 71°.
Pressure30.03 inHg
Wind9 mph NE
Humidity59%
Visibility—
Dew point64°
Wed, 1986° / 69°0.44
86 °
Chicago, Wednesday, 19 August
Rain. High 86°, low 69°.
Pressure29.91 inHg
Wind8.1 mph SW
Humidity53%
Visibility—
Dew point64°
Thu, 2075° / 69°0.03
75 °
Chicago, Thursday, 20 August
Light rain. High 75°, low 69°.
Pressure29.88 inHg
Wind9.6 mph N
Humidity72%
Visibility—
Dew point65°
Fri, 2176° / 67°0
76 °
Chicago, Friday, 21 August
Partly cloudy. High 76°, low 67°.
Pressure29.97 inHg
Wind9.3 mph NE
Humidity59%
Visibility—
Dew point60°
Sat, 2275° / 62°0.01
75 °
Chicago, Saturday, 22 August
Light rain. High 75°, low 62°.
Pressure29.94 inHg
Wind16.3 mph N
Humidity71%
Visibility—
Dew point61°
Sun, 2365° / 59°0
65 °
Chicago, Sunday, 23 August
Mostly clear. High 65°, low 59°.
Pressure30.24 inHg
Wind13 mph NE
Humidity47%
Visibility—
Dew point44°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2480° / 67°0.14
80 °
Chicago, Monday, 24 August
Climate normal for this date — 60-year average.
Average high80°
Average low67°
Average precipitation0.14 in
Chance of precipitation30%
Record high99° (2023)
Record low57° (1966)
Tue, 2580° / 66°0.08
80 °
Chicago, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high80°
Average low66°
Average precipitation0.08 in
Chance of precipitation28%
Record high92° (2024)
Record low54° (2017)
Wed, 2681° / 68°0.16
81 °
Chicago, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high81°
Average low68°
Average precipitation0.16 in
Chance of precipitation33%
Record high96° (2024)
Record low56° (2025)
Thu, 2780° / 68°0.14
80 °
Chicago, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high80°
Average low68°
Average precipitation0.14 in
Chance of precipitation37%
Record high97° (2024)
Record low57° (2025)
Fri, 2880° / 67°0.14
80 °
Chicago, Friday, 28 August
Climate normal for this date — 60-year average.
Average high80°
Average low67°
Average precipitation0.14 in
Chance of precipitation37%
Record high92° (1984)
Record low52° (1986)
Sat, 2980° / 67°0.11
80 °
Chicago, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high80°
Average low67°
Average precipitation0.11 in
Chance of precipitation28%
Record high93° (1984)
Record low50° (1965)
Sun, 3079° / 66°0.09
79 °
Chicago, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high79°
Average low66°
Average precipitation0.09 in
Chance of precipitation28%
Record high93° (2013)
Record low55° (1986)
Mon, 3178° / 66°0.06
78 °
Chicago, Monday, 31 August
Climate normal for this date — 60-year average.
Average high78°
Average low66°
Average precipitation0.06 in
Chance of precipitation23%
Record high90° (2012)
Record low57° (1992)
Tue, 0178° / 65°0.13
78 °
Chicago, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high78°
Average low65°
Average precipitation0.13 in
Chance of precipitation30%
Record high93° (2011)
Record low55° (1967)
Wed, 0279° / 66°0.06
79 °
Chicago, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high79°
Average low66°
Average precipitation0.06 in
Chance of precipitation25%
Record high91° (2011)
Record low52° (1965)
Thu, 0379° / 65°0.08
79 °
Chicago, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high79°
Average low65°
Average precipitation0.08 in
Chance of precipitation25%
Record high94° (2023)
Record low53° (1974)
Fri, 0477° / 65°0.09
77 °
Chicago, Friday, 4 September
Climate normal for this date — 60-year average.
Average high77°
Average low65°
Average precipitation0.09 in
Chance of precipitation33%
Record high92° (2023)
Record low51° (2025)
Sat, 0578° / 64°0.07
78 °
Chicago, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high78°
Average low64°
Average precipitation0.07 in
Chance of precipitation27%
Record high91° (2023)
Record low54° (2010)
Sun, 0677° / 64°0.1
77 °
Chicago, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high77°
Average low64°
Average precipitation0.1 in
Chance of precipitation38%
Record high92° (1990)
Record low51° (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 Chicago, 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 Chicago, 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.