Monthly outlook for Phoenix, IL: average high 78.9°, average low 65.9°. That is 0.6° below the climate normal for August. Precipitation is expected on 6 days (about 2.7 inches), against a normal of 6 days and 1.9 inches. The warmest day looks like 11 August (86.4°), the coolest 23 August (55.9°).
78.9°/65.9°
Average high / low
−0.6°
Below normal
6 / 6
Wet days / normal
2.7 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
79.5°
80.2°
-0.4°
18 August – 27 August
77.9°
80.1°
-1.2°
28 August – 6 September
at normal
78.6°
—
August records over 66 years
98.1°24 August 2023All-time high
49.3°29 August 1965All-time low
Climate normals and records are computed from the nearest reference point — Calumet Park (4 mi).
Sun, 0983° / 66°1.73
83 °
Phoenix, Sunday, 9 August
Heavy rain. High 83°, low 66°.
Pressure29.91 inHg
Wind6 mph SW
Humidity75%
Visibility6.2 mi
Dew point73°
Mon, 1082° / 73°0.11
82 °
Phoenix, Monday, 10 August
Rain. High 82°, low 73°.
Pressure29.91 inHg
Wind4.8 mph SE
Humidity70%
Visibility6.2 mi
Dew point71°
Tue, 1186° / 73°0.19
86 °
Phoenix, Tuesday, 11 August
Rain. High 86°, low 73°.
Pressure29.77 inHg
Wind14.4 mph SW
Humidity67%
Visibility6.2 mi
Dew point71°
Wed, 1282° / 70°0.01
82 °
Phoenix, Wednesday, 12 August
Light rain. High 82°, low 70°.
Pressure29.85 inHg
Wind6 mph NE
Humidity66%
Visibility6.2 mi
Dew point65°
Thu, 1372° / 65°0.02
72 °
Phoenix, Thursday, 13 August
Light rain. High 72°, low 65°.
Pressure29.94 inHg
Wind10.6 mph NE
Humidity66%
Visibility—
Dew point59°
Fri, 1474° / 62°0
74 °
Phoenix, Friday, 14 August
Clear. High 74°, low 62°.
Pressure30.18 inHg
Wind10.6 mph NE
Humidity47%
Visibility—
Dew point51°
Sat, 1577° / 59°0
77 °
Phoenix, Saturday, 15 August
Overcast. High 77°, low 59°.
Pressure30.33 inHg
Wind5.6 mph S
Humidity45%
Visibility—
Dew point50°
Sun, 1679° / 60°0
79 °
Phoenix, Sunday, 16 August
Mostly clear. High 79°, low 60°.
Pressure30.21 inHg
Wind9.6 mph S
Humidity49%
Visibility—
Dew point55°
Mon, 1776° / 69°0.11
76 °
Phoenix, Monday, 17 August
Light rain. High 76°, low 69°.
Pressure30.00 inHg
Wind6.1 mph S
Humidity89%
Visibility—
Dew point68°
Tue, 1883° / 69°0
83 °
Phoenix, Tuesday, 18 August
Partly cloudy. High 83°, low 69°.
Pressure30.00 inHg
Wind8.6 mph NE
Humidity56%
Visibility—
Dew point64°
Wed, 1985° / 67°0.4
85 °
Phoenix, Wednesday, 19 August
Rain. High 85°, low 67°.
Pressure29.91 inHg
Wind8.2 mph SW
Humidity58%
Visibility—
Dew point66°
Thu, 2078° / 68°0.06
78 °
Phoenix, Thursday, 20 August
Light rain. High 78°, low 68°.
Pressure29.88 inHg
Wind9.4 mph N
Humidity66%
Visibility—
Dew point65°
Fri, 2178° / 66°0
78 °
Phoenix, Friday, 21 August
Partly cloudy. High 78°, low 66°.
Pressure29.97 inHg
Wind9.4 mph NE
Humidity55%
Visibility—
Dew point59°
Sat, 2278° / 63°0.02
78 °
Phoenix, Saturday, 22 August
Light rain. High 78°, low 63°.
Pressure29.91 inHg
Wind14.7 mph N
Humidity64%
Visibility—
Dew point63°
Sun, 2366° / 56°0
66 °
Phoenix, Sunday, 23 August
Mostly clear. High 66°, low 56°.
Pressure30.24 inHg
Wind12.4 mph NE
Humidity43%
Visibility—
Dew point41°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2480° / 66°0.14
80 °
Phoenix, Monday, 24 August
Climate normal for this date — 60-year average.
Average high80°
Average low66°
Average precipitation0.14 in
Chance of precipitation28%
Record high98° (2023)
Record low57° (1966)
Tue, 2580° / 66°0.07
80 °
Phoenix, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high80°
Average low66°
Average precipitation0.07 in
Chance of precipitation27%
Record high92° (2021)
Record low53° (2017)
Wed, 2681° / 67°0.17
81 °
Phoenix, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high81°
Average low67°
Average precipitation0.17 in
Chance of precipitation35%
Record high94° (2024)
Record low54° (2025)
Thu, 2781° / 67°0.14
81 °
Phoenix, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high81°
Average low67°
Average precipitation0.14 in
Chance of precipitation37%
Record high96° (2024)
Record low54° (2025)
Fri, 2880° / 67°0.15
80 °
Phoenix, Friday, 28 August
Climate normal for this date — 60-year average.
Average high80°
Average low67°
Average precipitation0.15 in
Chance of precipitation37%
Record high92° (1984)
Record low51° (1986)
Sat, 2980° / 66°0.1
80 °
Phoenix, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high80°
Average low66°
Average precipitation0.1 in
Chance of precipitation28%
Record high93° (1984)
Record low49° (1965)
Sun, 3079° / 66°0.09
79 °
Phoenix, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high79°
Average low66°
Average precipitation0.09 in
Chance of precipitation30%
Record high92° (2013)
Record low54° (1986)
Mon, 3179° / 65°0.06
79 °
Phoenix, Monday, 31 August
Climate normal for this date — 60-year average.
Average high79°
Average low65°
Average precipitation0.06 in
Chance of precipitation23%
Record high89° (2012)
Record low55° (2023)
Tue, 0179° / 65°0.13
79 °
Phoenix, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high79°
Average low65°
Average precipitation0.13 in
Chance of precipitation30%
Record high94° (2011)
Record low54° (1967)
Wed, 0279° / 65°0.06
79 °
Phoenix, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high79°
Average low65°
Average precipitation0.06 in
Chance of precipitation27%
Record high92° (2011)
Record low52° (1965)
Thu, 0379° / 65°0.07
79 °
Phoenix, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high79°
Average low65°
Average precipitation0.07 in
Chance of precipitation23%
Record high93° (2023)
Record low53° (1974)
Fri, 0478° / 64°0.09
78 °
Phoenix, Friday, 4 September
Climate normal for this date — 60-year average.
Average high78°
Average low64°
Average precipitation0.09 in
Chance of precipitation33%
Record high91° (2023)
Record low50° (2025)
Sat, 0578° / 64°0.07
78 °
Phoenix, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high78°
Average low64°
Average precipitation0.07 in
Chance of precipitation27%
Record high90° (2023)
Record low53° (2010)
Sun, 0677° / 64°0.1
77 °
Phoenix, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high77°
Average low64°
Average precipitation0.1 in
Chance of precipitation37%
Record high91° (1990)
Record low49° (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 Phoenix, 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 Phoenix, 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.