Monthly outlook for Evanston, IL: average high 77.5°, average low 67.3°. That is 0.7° below the climate normal for August. Precipitation is expected on 7 days (about 2.5 inches), against a normal of 6 days and 1.8 inches. The warmest day looks like 19 August (83°), the coolest 23 August (58.8°).
77.5°/67.3°
Average high / low
−0.7°
Below normal
7 / 6
Wet days / normal
2.5 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
79.4°
78.9°
+0.3°
18 August – 27 August
74.3°
78.6°
-2.4°
28 August – 6 September
at normal
77.2°
—
August records over 66 years
99.7°24 August 2023All-time high
52.3°22 August 2024All-time low
Sun, 0983° / 67°1.38
83 °
Evanston, Sunday, 9 August
Heavy rain. High 83°, low 67°.
Pressure29.97 inHg
Wind13.5 mph NW
Humidity93%
Visibility—
Dew point65°
Mon, 1082° / 73°0.18
82 °
Evanston, Monday, 10 August
Rain. High 82°, low 73°.
Pressure29.88 inHg
Wind4.2 mph S
Humidity84%
Visibility6.2 mi
Dew point70°
Tue, 1182° / 72°0.28
82 °
Evanston, Tuesday, 11 August
Rain. High 82°, low 72°.
Pressure29.80 inHg
Wind10.4 mph N
Humidity68%
Visibility6.2 mi
Dew point70°
Wed, 1282° / 70°0.02
82 °
Evanston, Wednesday, 12 August
Light rain. High 82°, low 70°.
Pressure29.85 inHg
Wind2.2 mph E
Humidity64%
Visibility6.2 mi
Dew point64°
Thu, 1373° / 67°0.08
73 °
Evanston, Thursday, 13 August
Light rain. High 73°, low 67°.
Pressure29.97 inHg
Wind13.9 mph NE
Humidity68%
Visibility—
Dew point60°
Fri, 1472° / 65°0
72 °
Evanston, Friday, 14 August
Clear. High 72°, low 65°.
Pressure30.21 inHg
Wind11.4 mph NE
Humidity52%
Visibility—
Dew point52°
Sat, 1576° / 63°0
76 °
Evanston, Saturday, 15 August
Overcast. High 76°, low 63°.
Pressure30.30 inHg
Wind9.4 mph E
Humidity44%
Visibility—
Dew point50°
Sun, 1680° / 64°0
80 °
Evanston, Sunday, 16 August
Partly cloudy. High 80°, low 64°.
Pressure30.18 inHg
Wind10 mph SW
Humidity44%
Visibility—
Dew point53°
Mon, 1780° / 69°0.05
80 °
Evanston, Monday, 17 August
Light rain. High 80°, low 69°.
Pressure30.00 inHg
Wind7.7 mph S
Humidity83%
Visibility—
Dew point65°
Tue, 1877° / 71°0.01
77 °
Evanston, Tuesday, 18 August
Light rain. High 77°, low 71°.
Pressure30.03 inHg
Wind9.1 mph NE
Humidity69%
Visibility—
Dew point66°
Wed, 1983° / 69°0.46
83 °
Evanston, Wednesday, 19 August
Rain. High 83°, low 69°.
Pressure29.91 inHg
Wind6.4 mph S
Humidity57%
Visibility—
Dew point64°
Thu, 2074° / 69°0.02
74 °
Evanston, Thursday, 20 August
Light rain. High 74°, low 69°.
Pressure29.91 inHg
Wind11.6 mph N
Humidity77%
Visibility—
Dew point66°
Fri, 2173° / 67°0
73 °
Evanston, Friday, 21 August
Partly cloudy. High 73°, low 67°.
Pressure30.00 inHg
Wind11 mph NE
Humidity68%
Visibility—
Dew point61°
Sat, 2275° / 62°0.05
75 °
Evanston, Saturday, 22 August
Light rain. High 75°, low 62°.
Pressure29.97 inHg
Wind20.5 mph NE
Humidity80%
Visibility—
Dew point60°
Sun, 2364° / 59°0
64 °
Evanston, Sunday, 23 August
Clear. High 64°, low 59°.
Pressure30.27 inHg
Wind17.7 mph NE
Humidity55%
Visibility—
Dew point46°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2479° / 68°0.12
79 °
Evanston, Monday, 24 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.12 in
Chance of precipitation30%
Record high100° (2023)
Record low58° (1966)
Tue, 2579° / 68°0.07
79 °
Evanston, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.07 in
Chance of precipitation23%
Record high92° (2024)
Record low56° (2017)
Wed, 2680° / 68°0.15
80 °
Evanston, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high80°
Average low68°
Average precipitation0.15 in
Chance of precipitation33%
Record high96° (2024)
Record low55° (2025)
Thu, 2779° / 69°0.11
79 °
Evanston, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high79°
Average low69°
Average precipitation0.11 in
Chance of precipitation32%
Record high97° (2024)
Record low57° (2025)
Fri, 2879° / 68°0.12
79 °
Evanston, Friday, 28 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.12 in
Chance of precipitation33%
Record high92° (2021)
Record low53° (1986)
Sat, 2979° / 68°0.11
79 °
Evanston, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high79°
Average low68°
Average precipitation0.11 in
Chance of precipitation30%
Record high91° (1984)
Record low53° (1965)
Sun, 3078° / 67°0.13
78 °
Evanston, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high78°
Average low67°
Average precipitation0.13 in
Chance of precipitation27%
Record high91° (2013)
Record low57° (1965)
Mon, 3177° / 66°0.07
77 °
Evanston, Monday, 31 August
Climate normal for this date — 60-year average.
Average high77°
Average low66°
Average precipitation0.07 in
Chance of precipitation22%
Record high89° (2012)
Record low58° (2025)
Tue, 0177° / 67°0.12
77 °
Evanston, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high77°
Average low67°
Average precipitation0.12 in
Chance of precipitation32%
Record high90° (2011)
Record low56° (1987)
Wed, 0278° / 67°0.05
78 °
Evanston, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high78°
Average low67°
Average precipitation0.05 in
Chance of precipitation25%
Record high89° (2023)
Record low53° (2017)
Thu, 0377° / 66°0.08
77 °
Evanston, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high77°
Average low66°
Average precipitation0.08 in
Chance of precipitation28%
Record high94° (2023)
Record low54° (1974)
Fri, 0476° / 66°0.08
76 °
Evanston, Friday, 4 September
Climate normal for this date — 60-year average.
Average high76°
Average low66°
Average precipitation0.08 in
Chance of precipitation30%
Record high92° (2023)
Record low50° (2025)
Sat, 0576° / 65°0.08
76 °
Evanston, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high76°
Average low65°
Average precipitation0.08 in
Chance of precipitation22%
Record high91° (2023)
Record low55° (2017)
Sun, 0676° / 65°0.1
76 °
Evanston, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high76°
Average low65°
Average precipitation0.1 in
Chance of precipitation35%
Record high90° (1990)
Record low50° (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 Evanston, 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 Evanston, 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.