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Iowa State University Department of Agronomy

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Freezing Dates

Using the NWS COOP data archive, significant dates relating to fall are extracted and presented on this page. The specific dates are the first occurance of that temperature and may have occured again in subsequent years.
The "Record Lows" columns show the first fall occurance of a low temperature. The "Average Lows" column shows when certain climatological thresholds are surpassed in the fall.

COOP Site: Record Lows: Average Lows:
Temp <= 32°F Temp <= 28°F Below 40°F Below 32°F Below 28°F
Temp: Date: Temp: Date:
SIBLEY-5-NNE 30 1974-09-03 23 1955-09-11 10-04 10-26 11-03
ROCK-RAPIDS 31 1974-09-03 26 1894-09-10 10-06 10-24 11-03
CARROLL-2-SSW 28 1974-09-03 28 1974-09-03 10-07 10-29 11-08
GRUNDY-CENTER 31 2007-09-15 27 1974-09-22 10-07 10-29 11-07
CASCADE 32 1955-09-11 28 1953-09-22 10-07 11-03 11-10
POCAHONTAS 30 2007-09-15 28 1983-09-20 10-07 10-28 11-05
CHEROKEE 31 1974-09-03 27 1955-09-11 10-07 10-26 11-04
ESTHERVILLE-2-N 30 2007-09-15 28 1991-09-20 10-07 10-28 11-05
CRESCO-1-NE 31 1975-09-13 27 1991-09-20 10-07 10-29 11-05
MANCHESTER-2 29 2007-09-15 27 1984-09-16 10-07 10-28 11-09
CLARION 32 1974-09-03 25 1974-09-22 10-09 10-28 11-07
HUMBOLDT-2 32 1976-09-17 26 1974-09-22 10-09 11-02 11-07
NORTHWOOD 31 1953-09-13 26 1974-09-22 10-09 11-02 11-05
SIOUX-RAPIDS 31 1974-09-03 28 1991-09-19 10-09 10-29 11-06
FOREST-CITY 31 2007-09-15 26 1974-09-22 10-09 11-02 11-08
Sheldon 32 1974-09-03 28 2007-09-15 10-09 10-28 11-04
PRIMGHAR 31 1984-09-15 27 1991-09-19 10-09 11-02 11-08
PERRY 32 1955-09-12 28 1974-09-22 10-09 11-03 11-10
HAWARDEN 31 1974-09-03 24 1991-09-19 10-09 10-28 11-04
BRITT 31 2007-09-15 25 1983-09-22 10-09 11-02 11-08
FORT-DODGE 32 1974-09-03 28 1995-09-22 10-09 11-02 11-10
VINTON 32 1953-09-13 28 1982-09-21 10-10 11-03 11-20
CHARLES-CITY 32 1955-09-12 28 1991-09-20 10-10 11-03 11-10
TRIPOLI-4-N 31 2007-09-15 27 1974-09-22 10-10 11-03 11-10
OELWEIN-2-S 28 1955-09-11 28 1955-09-11 10-10 11-02 11-10
AUDUBON 30 1955-09-12 28 1991-09-20 10-10 11-02 11-10
ANAMOSA-1-WNW 29 1955-09-12 27 1956-09-20 10-10 11-03 11-12
OAKLAND-2-E 32 1974-09-03 28 1995-09-22 10-10 11-03 11-10
FAYETTE 32 1949-09-01 27 1902-09-12 10-10 10-28 11-10
WAUKON 32 1956-09-20 27 1984-09-26 10-10 11-02 11-09
Eldora 32 1962-09-20 28 1974-09-22 10-10 11-03 11-10
DECORAH-2-N 32 1915-08-30 28 1946-09-02 10-10 11-02 11-10
MASON-CITY 30 1915-08-30 28 1923-09-14 10-10 11-01 11-08
EMMETSBURG 31 1991-09-19 24 1995-09-22 10-10 11-02 11-08
INDEPENDENCE-2-W 32 1974-09-03 28 1975-09-13 10-10 11-03 11-10
IOWA-FALLS 32 1976-09-10 26 1974-09-22 10-10 11-02 11-07
TOLEDO 31 2007-09-15 28 1962-09-20 10-10 11-03 11-10
Boone 32 1975-09-12 28 1981-09-18 10-10 11-01 11-04
SAC-CITY 32 1974-09-03 27 1974-09-22 10-10 11-02 11-11
WATERLOO 32 1917-09-11 28 1929-09-18 10-13 11-02 11-10
WEBSTER-CITY 30 1955-09-11 25 1929-09-18 10-13 11-02 11-10
SIOUX-CITY-WSO-AP 32 2007-09-15 25 1995-09-22 10-15 11-02 11-08
HARLAN 29 1991-09-19 27 1951-09-28 10-17 11-03 11-10
OSAGE 32 2007-09-15 28 1974-09-22 10-17 11-03 11-10
ROCKWELL-CITY 32 1902-09-12 28 1929-09-18 10-17 11-02 11-10
MAQUOKETA-2-W 31 1917-09-11 28 1983-09-23 10-17 11-04 11-13
HAMPTON-2-NW 32 1955-09-11 28 1955-09-12 10-17 11-02 11-10
STORM-LAKE-2-E 32 1902-09-12 28 1929-09-18 10-17 11-02 11-08
GRINNELL-3-SW 31 1976-09-10 27 1991-09-20 10-17 11-03 11-12
ALGONA 29 1893-09-02 27 1929-09-18 10-17 11-02 11-10
NEW-HAMPTON 28 1949-09-01 28 1949-09-01 10-17 11-02 11-10
LEMARS 25 1893-09-02 25 1893-09-02 10-17 10-29 11-08
ATLANTIC-1-NE 30 1893-09-02 28 1902-09-12 10-17 11-02 11-10
MARSHALLTOWN 31 1955-09-12 28 1896-09-20 10-17 11-02 11-11
GUTHRIE-CENTER 31 1893-09-02 28 1991-09-19 10-17 11-02 11-11
NEWTON 29 1974-09-22 27 1972-09-30 10-18 11-05 11-21
CASTANA-EXP-FARM 30 1991-09-19 28 1995-09-22 10-18 11-03 11-19
BELLE-PLAINE 32 1955-09-12 28 1991-09-20 10-18 11-04 11-19
CORNING 32 1902-09-12 27 1983-09-21 10-18 11-03 11-19
CHARITON 32 1955-09-12 28 1991-09-20 10-18 11-04 11-20
OSCEOLA-3-WSW 31 2007-09-15 28 1974-09-22 10-18 11-04 11-20
RED-OAK 32 1993-09-15 28 1995-09-22 10-18 11-04 11-20
JEFFERSON 32 2007-09-16 23 1974-10-02 10-18 11-04 11-19
BELLEVUE-L-AND-D-12 31 1991-09-20 25 1995-09-23 10-18 11-04 11-21
LOGAN 30 1902-09-12 28 1902-09-13 10-18 11-02 11-12
WILLIAMSBURG 31 1955-09-12 28 1991-09-20 10-18 11-04 11-20
ANKENY-3-S 32 1991-09-20 28 1984-09-26 10-18 11-04 11-20
WINTERSET 31 1955-09-12 28 1962-09-20 10-18 11-04 11-10
AMES-8-WSW 31 1902-09-13 26 1918-09-21 10-18 11-02 11-12
ALLISON 30 1991-09-20 28 1984-09-26 10-18 11-03 11-16
DENISON 29 1902-09-12 21 1918-09-21 10-18 11-02 11-12
Creston 28 1991-09-19 28 1991-09-19 10-18 11-03 11-20
Lamoni 32 1991-09-19 24 1974-10-02 10-19 11-05 11-21
KNOXVILLE 31 1991-09-19 27 1974-10-02 10-19 11-07 11-21
CENTERVILLE 32 1991-09-19 27 1979-10-05 10-19 11-05 11-23
BLOOMFIELD 31 1991-09-20 25 1974-10-02 10-19 11-05 11-21
CLINTON-1 22 1924-08-31 22 1924-08-31 10-19 11-06 11-22
IOWA-CITY 32 1956-09-20 24 1958-10-01 10-19 11-06 11-21
MUSCATINE 29 1991-09-20 26 1984-09-29 10-19 11-10 11-24
MOUNT-PLEASANT 29 1991-09-20 25 1974-10-02 10-19 11-10 11-21
BEDFORD-1-NNW 27 1991-09-19 27 1991-09-19 10-19 11-04 11-20
SHENANDOAH-1-NE 30 1980-09-17 26 1983-09-23 10-19 11-05 11-20
ONAWA 30 1955-09-11 28 1991-09-19 10-19 11-02 11-11
Des Moines Airport 31 1995-09-22 28 1984-09-29 10-19 11-05 11-20
Iowa Average 31 1902-09-13 27 1926-09-26 10-19 11-03 11-19
TIPTON 32 1902-09-13 28 1991-09-20 10-19 11-05 11-21
OSKALOOSA 31 1902-09-13 27 1991-09-20 10-19 11-05 11-21
SIGOURNEY 31 1995-09-22 28 1964-09-28 10-19 11-05 11-21
CEDAR-RAPIDS-1 32 2007-09-15 24 1926-09-26 10-19 11-05 11-21
GLENWOOD 27 1901-09-18 27 1901-09-18 10-19 11-04 11-21
GUTTENBERG-L-AND-D-10 32 1973-09-18 28 1984-09-29 10-19 11-05 11-21
GREENFIELD 32 1981-09-17 28 1995-09-22 10-19 11-04 11-20
INDIANOLA-2-SSW 30 1979-09-15 28 1979-09-22 10-19 11-08 11-21
CLARINDA 31 1902-09-13 28 1918-09-21 10-19 11-03 11-19
MOUNT-AYR 32 1902-09-13 28 1991-09-19 10-23 11-05 11-21
FAIRFIELD 32 1917-09-11 28 1918-09-21 10-24 11-08 11-22
KEOSAUQUA 31 1917-09-11 28 1916-09-18 10-24 11-09 11-22
WASHINGTON 30 1902-09-13 28 1983-09-23 10-24 11-08 11-22
Ottumwa 29 1981-08-03 27 1984-09-29 10-24 11-08 11-24
ALBIA 31 1991-09-19 25 1984-09-29 10-25 11-06 11-21
DUBUQUE-LOCK-AND-DAM 31 1956-09-20 24 1899-09-30 10-25 11-10 11-22
SIDNEY 30 1991-09-19 28 1995-09-22 10-27 11-05 11-24
Burlington 32 1991-09-20 26 2003-10-02 10-27 11-10 11-24
Le Claire L&D 14 32 1984-09-29 25 1974-10-02 10-28 11-11 11-24
FORT-MADISON 32 1983-09-23 27 1974-10-02 10-28 11-10 11-24