Monthly outlook for Jefferson, SD: average high 94.3°, average low 65.3°. That is 6.7° above the climate normal for August. Precipitation is expected on 4 days (about 0.6 inches), against a normal of 5 days and 1.9 inches. The warmest day looks like 10 August (106.9°), the coolest 23 August (51.1°).
94.3°/65.3°
Average high / low
+6.7°
Above normal
4 / 5
Wet days / normal
0.6 in
Precipitation this month
Ten-day blocks vs climate normal
Period
Forecast high
Normal
Difference
8 August – 17 August
95.3°
82.2°
+7.3°
18 August – 27 August
92.6°
82.2°
+5.8°
28 August – 6 September
at normal
81°
—
August records over 66 years
102.6°2 August 2022All-time high
44.8°28 August 1986All-time low
Climate normals and records are computed from the nearest reference point — Sioux City (12 mi).
Sun, 0990° / 72°0
90 °
Jefferson, Sunday, 9 August
Partly cloudy. High 90°, low 72°.
Pressure29.71 inHg
Wind8.2 mph N
Humidity28%
Visibility6.2 mi
Dew point60°
Mon, 10107° / 68°0
107 °
Jefferson, Monday, 10 August
Overcast. High 107°, low 68°.
Pressure29.77 inHg
Wind9 mph SE
Humidity28%
Visibility6.2 mi
Dew point60°
Tue, 11103° / 68°0.01
103 °
Jefferson, Tuesday, 11 August
Light rain. High 103°, low 68°.
Pressure29.74 inHg
Wind12.9 mph N
Humidity31%
Visibility6.2 mi
Dew point60°
Wed, 12103° / 72°0.01
103 °
Jefferson, Wednesday, 12 August
Light rain. High 103°, low 72°.
Pressure29.80 inHg
Wind10.4 mph SE
Humidity30%
Visibility6.2 mi
Dew point59°
Thu, 1390° / 64°0.16
90 °
Jefferson, Thursday, 13 August
Light rain. High 90°, low 64°.
Pressure29.94 inHg
Wind13.6 mph E
Humidity30%
Visibility—
Dew point48°
Fri, 1490° / 59°0
90 °
Jefferson, Friday, 14 August
Overcast. High 90°, low 59°.
Pressure30.15 inHg
Wind11.5 mph S
Humidity25%
Visibility—
Dew point42°
Sat, 1590° / 60°0
90 °
Jefferson, Saturday, 15 August
Overcast. High 90°, low 60°.
Pressure30.09 inHg
Wind14.5 mph SE
Humidity37%
Visibility—
Dew point54°
Sun, 1699° / 69°0.13
99 °
Jefferson, Sunday, 16 August
Light rain. High 99°, low 69°.
Pressure29.94 inHg
Wind11.7 mph S
Humidity46%
Visibility—
Dew point65°
Mon, 1798° / 70°0.08
98 °
Jefferson, Monday, 17 August
Light rain. High 98°, low 70°.
Pressure29.97 inHg
Wind9.9 mph N
Humidity43%
Visibility—
Dew point65°
Tue, 18102° / 69°0
102 °
Jefferson, Tuesday, 18 August
Overcast. High 102°, low 69°.
Pressure29.91 inHg
Wind9.8 mph SW
Humidity33%
Visibility—
Dew point59°
Wed, 19102° / 70°0.11
102 °
Jefferson, Wednesday, 19 August
Light rain. High 102°, low 70°.
Pressure29.83 inHg
Wind15.7 mph E
Humidity28%
Visibility—
Dew point55°
Thu, 2091° / 65°0.03
91 °
Jefferson, Thursday, 20 August
Light rain. High 91°, low 65°.
Pressure29.94 inHg
Wind9.4 mph NE
Humidity30%
Visibility—
Dew point50°
Fri, 2196° / 65°0
96 °
Jefferson, Friday, 21 August
Clear. High 96°, low 65°.
Pressure29.91 inHg
Wind11.3 mph W
Humidity28%
Visibility—
Dew point51°
Sat, 2282° / 66°0.02
82 °
Jefferson, Saturday, 22 August
Light rain. High 82°, low 66°.
Pressure30.00 inHg
Wind16.5 mph NE
Humidity54%
Visibility—
Dew point57°
Sun, 2383° / 51°0
83 °
Jefferson, Sunday, 23 August
Clear. High 83°, low 51°.
Pressure30.15 inHg
Wind11.3 mph SE
Humidity24%
Visibility—
Dew point35°
From day 17 onward the outlook is built from 60-year climate statistics
Mon, 2482° / 66°0.05
82 °
Jefferson, Monday, 24 August
Climate normal for this date — 60-year average.
Average high82°
Average low66°
Average precipitation0.05 in
Chance of precipitation18%
Record high99° (2023)
Record low52° (2015)
Tue, 2582° / 65°0.09
82 °
Jefferson, Tuesday, 25 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.09 in
Chance of precipitation20%
Record high97° (1991)
Record low50° (2015)
Wed, 2682° / 65°0.11
82 °
Jefferson, Wednesday, 26 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.11 in
Chance of precipitation37%
Record high95° (1976)
Record low53° (1988)
Thu, 2782° / 65°0.09
82 °
Jefferson, Thursday, 27 August
Climate normal for this date — 60-year average.
Average high82°
Average low65°
Average precipitation0.09 in
Chance of precipitation28%
Record high96° (1984)
Record low51° (1986)
Fri, 2882° / 64°0.14
82 °
Jefferson, Friday, 28 August
Climate normal for this date — 60-year average.
Average high82°
Average low64°
Average precipitation0.14 in
Chance of precipitation25%
Record high99° (1984)
Record low45° (1986)
Sat, 2982° / 64°0.07
82 °
Jefferson, Saturday, 29 August
Climate normal for this date — 60-year average.
Average high82°
Average low64°
Average precipitation0.07 in
Chance of precipitation18%
Record high98° (2012)
Record low51° (2018)
Sun, 3082° / 64°0.09
82 °
Jefferson, Sunday, 30 August
Climate normal for this date — 60-year average.
Average high82°
Average low64°
Average precipitation0.09 in
Chance of precipitation30%
Record high101° (2012)
Record low50° (2009)
Mon, 3181° / 64°0.09
81 °
Jefferson, Monday, 31 August
Climate normal for this date — 60-year average.
Average high81°
Average low64°
Average precipitation0.09 in
Chance of precipitation32%
Record high92° (1990)
Record low49° (1967)
Tue, 0181° / 63°0.08
81 °
Jefferson, Tuesday, 1 September
Climate normal for this date — 60-year average.
Average high81°
Average low63°
Average precipitation0.08 in
Chance of precipitation28%
Record high92° (1970)
Record low48° (1974)
Wed, 0281° / 63°0.08
81 °
Jefferson, Wednesday, 2 September
Climate normal for this date — 60-year average.
Average high81°
Average low63°
Average precipitation0.08 in
Chance of precipitation28%
Record high96° (2023)
Record low50° (1974)
Thu, 0380° / 63°0.13
80 °
Jefferson, Thursday, 3 September
Climate normal for this date — 60-year average.
Average high80°
Average low63°
Average precipitation0.13 in
Chance of precipitation27%
Record high95° (2023)
Record low42° (1974)
Fri, 0480° / 62°0.11
80 °
Jefferson, Friday, 4 September
Climate normal for this date — 60-year average.
Average high80°
Average low62°
Average precipitation0.11 in
Chance of precipitation22%
Record high96° (2012)
Record low46° (1974)
Sat, 0580° / 62°0.08
80 °
Jefferson, Saturday, 5 September
Climate normal for this date — 60-year average.
Average high80°
Average low62°
Average precipitation0.08 in
Chance of precipitation32%
Record high94° (1990)
Record low42° (1962)
Sun, 0681° / 62°0.05
81 °
Jefferson, Sunday, 6 September
Climate normal for this date — 60-year average.
Average high81°
Average low62°
Average precipitation0.05 in
Chance of precipitation17%
Record high99° (1976)
Record low44° (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 Jefferson, SD 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 Jefferson, SD 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.