Monthly outlook for Vandalia, IA: average high 82.2°, average low 63.6°. That is 0.5° above the climate normal for August. Precipitation is expected on 4 days (about 0.4 inches), against a normal of 5 days and 2.3 inches. The warmest day looks like 9 August (94.9°), the coolest 21 August (50.1°).
82.2°/63.6°
Average high / low
+0.5°
Above normal
4 / 5
Wet days / normal
0.4 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
82.3°
81.2°
+0.6°
18 August – 27 August
81.9°
81.4°
+0.3°
28 August – 6 September
at normal
79.9°
—
August records over 66 years
100.4°16 August 1988All-time high
43.9°28 August 1986All-time low
Climate normals and records are computed from the nearest reference point — Mitchellville (9 mi).
Sun, 0995° / 74°0
95 °
Vandalia, Sunday, 9 August
Mostly clear. High 95°, low 74°.
Pressure29.77 inHg
Wind14.8 mph SW
Humidity53%
Visibility6.2 mi
Dew point70°
Mon, 1089° / 74°0.09
89 °
Vandalia, Monday, 10 August
Rain. High 89°, low 74°.
Pressure29.83 inHg
Wind3.8 mph S
Humidity56%
Visibility6.2 mi
Dew point69°
Tue, 1191° / 69°0
91 °
Vandalia, Tuesday, 11 August
Mostly clear. High 91°, low 69°.
Pressure29.77 inHg
Wind4.2 mph SW
Humidity53%
Visibility6.2 mi
Dew point69°
Wed, 1286° / 70°0.04
86 °
Vandalia, Wednesday, 12 August
Light rain. High 86°, low 70°.
Pressure29.88 inHg
Wind5 mph NE
Humidity72%
Visibility6.2 mi
Dew point69°
Thu, 1373° / 61°0.16
73 °
Vandalia, Thursday, 13 August
Light rain. High 73°, low 61°.
Pressure29.94 inHg
Wind13.1 mph NE
Humidity70%
Visibility—
Dew point61°
Fri, 1477° / 60°0
77 °
Vandalia, Friday, 14 August
Overcast. High 77°, low 60°.
Pressure30.09 inHg
Wind12 mph E
Humidity57%
Visibility—
Dew point58°
Sat, 1568° / 61°0.08
68 °
Vandalia, Saturday, 15 August
Light rain. High 68°, low 61°.
Pressure30.21 inHg
Wind16.2 mph E
Humidity93%
Visibility—
Dew point59°
Sun, 1678° / 63°0
78 °
Vandalia, Sunday, 16 August
Overcast. High 78°, low 63°.
Pressure30.12 inHg
Wind5.6 mph NE
Humidity77%
Visibility—
Dew point64°
Mon, 1784° / 67°0.02
84 °
Vandalia, Monday, 17 August
Light rain. High 84°, low 67°.
Pressure30.03 inHg
Wind7.1 mph S
Humidity62%
Visibility—
Dew point66°
Tue, 1892° / 68°0
92 °
Vandalia, Tuesday, 18 August
Partly cloudy. High 92°, low 68°.
Pressure29.94 inHg
Wind11.6 mph S
Humidity60%
Visibility—
Dew point69°
Wed, 1976° / 62°0.01
76 °
Vandalia, Wednesday, 19 August
Light rain. High 76°, low 62°.
Pressure30.03 inHg
Wind15.3 mph N
Humidity71%
Visibility—
Dew point61°
Thu, 2069° / 56°0.01
69 °
Vandalia, Thursday, 20 August
Light rain. High 69°, low 56°.
Pressure30.09 inHg
Wind14.6 mph NE
Humidity54%
Visibility—
Dew point50°
Fri, 2172° / 50°0
72 °
Vandalia, Friday, 21 August
Overcast. High 72°, low 50°.
Pressure30.06 inHg
Wind10.2 mph SE
Humidity56%
Visibility—
Dew point49°
Sat, 2292° / 59°0
92 °
Vandalia, Saturday, 22 August
Partly cloudy. High 92°, low 59°.
Pressure29.80 inHg
Wind10.6 mph NW
Humidity46%
Visibility—
Dew point59°
Sun, 2390° / 64°0
90 °
Vandalia, Sunday, 23 August
Clear. High 90°, low 64°.
Pressure29.94 inHg
Wind8.3 mph W
Humidity32%
Visibility—
Dew point50°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2482° / 65°0.09
82 °
Vandalia, Monday, 24 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.09 in
Chance of precipitation18%
Record high96° (2023)
Record low49° (1966)
Tue, 2582° / 65°0.13
82 °
Vandalia, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.13 in
Chance of precipitation38%
Record high96° (2003)
Record low52° (2025)
Wed, 2682° / 65°0.19
82 °
Vandalia, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.19 in
Chance of precipitation27%
Record high95° (2013)
Record low50° (2015)
Thu, 2781° / 65°0.16
81 °
Vandalia, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high81°
Average low65°
Average precipitation0.16 in
Chance of precipitation33%
Record high96° (2013)
Record low53° (1967)
Fri, 2882° / 64°0.17
82 °
Vandalia, Friday, 28 August
Climate normal for this date — 60-year average.
Average high82°
Average low64°
Average precipitation0.17 in
Chance of precipitation37%
Record high96° (1984)
Record low44° (1986)
Sat, 2982° / 64°0.11
82 °
Vandalia, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high82°
Average low64°
Average precipitation0.11 in
Chance of precipitation25%
Record high94° (1984)
Record low50° (1988)
Sun, 3080° / 64°0.13
80 °
Vandalia, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high80°
Average low64°
Average precipitation0.13 in
Chance of precipitation25%
Record high97° (2013)
Record low50° (2009)
Mon, 3180° / 63°0.09
80 °
Vandalia, Monday, 31 August
Climate normal for this date — 60-year average.
Average high80°
Average low63°
Average precipitation0.09 in
Chance of precipitation25%
Record high94° (2000)
Record low46° (2009)
Tue, 0180° / 63°0.09
80 °
Vandalia, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high80°
Average low63°
Average precipitation0.09 in
Chance of precipitation22%
Record high95° (1984)
Record low46° (1967)
Wed, 0280° / 63°0.09
80 °
Vandalia, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high80°
Average low63°
Average precipitation0.09 in
Chance of precipitation28%
Record high95° (2000)
Record low51° (1974)
Thu, 0379° / 63°0.08
79 °
Vandalia, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high79°
Average low63°
Average precipitation0.08 in
Chance of precipitation22%
Record high94° (2023)
Record low42° (1974)
Fri, 0479° / 62°0.08
79 °
Vandalia, Friday, 4 September
Climate normal for this date — 60-year average.
Average high79°
Average low62°
Average precipitation0.08 in
Chance of precipitation30%
Record high95° (2023)
Record low43° (1974)
Sat, 0579° / 61°0.07
79 °
Vandalia, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high79°
Average low61°
Average precipitation0.07 in
Chance of precipitation22%
Record high92° (2023)
Record low44° (1962)
Sun, 0679° / 62°0.12
79 °
Vandalia, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high79°
Average low62°
Average precipitation0.12 in
Chance of precipitation28%
Record high93° (2020)
Record low45° (1962)
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 Vandalia, IA 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 Vandalia, IA 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.