Record envelope, standing records and threshold days for Waterloo (USC00138704), Iowa, United States, with 56 years of record.
Key Facts for Waterloo
Waterloo (USC00138704) is a weather station in Iowa, United States at 42.52 latitude and -92.33 longitude, 256 m (840 ft) above sea level.
The station reports from 1895 to 1950, 56 years of record.
1,464 records set at Waterloo still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Waterloo set a daily record low maximum temperature of -12.2 C (10.0 F) on 25 February 1950.
About the Station
Location: Iowa, United States, 42.52 latitude, -92.33 longitude.
Elevation: 256 m (840 ft).
Period of record: 1895 to 1950, 56 years.
Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
0 days at or beyond a record
Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Waterloo. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Waterloo, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
16.1 C (61.0 F)
-36.1 C (-33.0 F)
n/a
n/a
Feb
21.7 C (71.1 F)
-34.4 C (-29.9 F)
n/a
n/a
Mar
30.0 C (86.0 F)
-27.8 C (-18.0 F)
n/a
n/a
Apr
35.0 C (95.0 F)
-10.6 C (12.9 F)
n/a
n/a
May
42.2 C (108.0 F)
-5.6 C (21.9 F)
n/a
n/a
Jun
41.7 C (107.1 F)
0.6 C (33.1 F)
n/a
n/a
Jul
44.4 C (111.9 F)
6.1 C (43.0 F)
n/a
n/a
Aug
43.3 C (109.9 F)
1.1 C (34.0 F)
n/a
n/a
Sep
38.9 C (102.0 F)
-7.2 C (19.0 F)
n/a
n/a
Oct
35.0 C (95.0 F)
-17.8 C (0.0 F)
n/a
n/a
Nov
28.3 C (82.9 F)
-22.8 C (-9.0 F)
n/a
n/a
Dec
18.3 C (64.9 F)
-33.9 C (-29.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Waterloo still stand. 1936 holds the most, with 61.
Standing records at Waterloo by the year they were set
Year set
Standing records
1895
28
1896
25
1897
37
1898
27
1899
30
1900
19
1901
35
1902
28
1903
20
1904
21
1905
12
1906
11
1907
23
1908
20
1909
31
1910
21
1911
34
1912
31
1913
32
1914
26
1915
27
1916
31
1917
48
1918
35
1919
13
1920
26
1921
30
1922
18
1923
17
1924
25
1925
41
1926
23
1927
17
1928
36
1929
18
1930
51
1931
41
1932
22
1933
27
1934
41
1935
24
1936
61
1937
22
1938
20
1939
19
1940
26
1941
17
1942
22
1943
24
1944
24
1945
19
1946
27
1947
22
1948
24
1949
12
1950
3
All-Time Record Progression
5 new records
5 all-time records were set at Waterloo between 22 January 1930 and 30 July 1942. Each dot is a new record.
When Waterloo set new all-time records
Date
Kind
Detail
1930-01-22
Record low minimum temperature
Record low minimum temperature -36.1 C (-33.0 F)
1936-02-17
Record snow depth
Record snow depth 63.5 cm (25.0 in)
1936-07-12
Record high maximum temperature
Record high maximum temperature 43.3 C (109.9 F)
1936-07-13
Record high maximum temperature
Record high maximum temperature 44.4 C (111.9 F)
1942-07-30
Record daily precipitation
Record daily precipitation 133.4 mm (5.3 in)
Wettest Day of Each Month
Jul: 133.4 mm (5.3 in)
The wettest day on record for each calendar month at Waterloo. The most was 133.4 mm (5.3 in) on 30 July 1942.
Record daily precipitation for each month at Waterloo
Month
Record daily precipitation (mm)
Date
Jan
45.0 mm (1.8 in)
3 January 1906
Feb
45.7 mm (1.8 in)
28 February 1948
Mar
47.0 mm (1.9 in)
29 March 1933
Apr
45.5 mm (1.8 in)
18 April 1909
May
64.0 mm (2.5 in)
27 May 1903
Jun
100.3 mm (3.9 in)
13 June 1947
Jul
133.4 mm (5.3 in)
30 July 1942
Aug
101.6 mm (4.0 in)
19 August 1912
Sep
114.3 mm (4.5 in)
19 September 1919
Oct
59.7 mm (2.4 in)
31 October 1900
Nov
64.8 mm (2.6 in)
5 November 1938
Dec
23.4 mm (0.9 in)
10 December 1911
Period of Record Coverage
1895 to 1950
Complete yearUnder 90 percent of days
56 years of record at Waterloo, 1895 to 1950. 1 years have data for under 90 percent of days and are left out of rankings: 1950.
Cooler than the station meanWarmer than the station mean
One stripe for each of 54 complete years at Waterloo, 1896 to 1949. Blue stripes are years cooler than the station's own mean of 8.8 C (47.9 F); red stripes are warmer. The coolest year was 1917, at 5.9 C (42.7 F), and the warmest was 1931, at 11.7 C (53.0 F). The strongest colour marks a difference of 2.9 C (5.2 F).
Annual mean temperature at Waterloo as warming stripes, 1896 to 1949
Year
Annual mean temperature
Difference from the station mean
1896
8.7 C
-0.14 C
1897
8.0 C
-0.80 C
1898
8.3 C
-0.54 C
1899
8.2 C
-0.59 C
1900
9.1 C
+0.29 C
1901
9.0 C
+0.15 C
1902
8.3 C
-0.50 C
1903
8.1 C
-0.71 C
1904
7.7 C
-1.16 C
1905
8.3 C
-0.58 C
1906
8.9 C
+0.10 C
1907
8.5 C
-0.29 C
1908
9.7 C
+0.82 C
1909
8.3 C
-0.57 C
1910
8.8 C
-0.04 C
1911
8.9 C
+0.08 C
1912
7.0 C
-1.85 C
1913
9.2 C
+0.39 C
1914
8.8 C
-0.07 C
1915
7.9 C
-0.89 C
1916
7.8 C
-1.08 C
1917
5.9 C
-2.89 C
1918
8.4 C
-0.41 C
1919
8.8 C
-0.06 C
1920
8.7 C
-0.17 C
1921
10.8 C
+2.01 C
1922
9.8 C
+0.95 C
1923
9.3 C
+0.51 C
1924
7.8 C
-1.03 C
1925
9.1 C
+0.26 C
1926
8.7 C
-0.10 C
1927
9.2 C
+0.33 C
1928
9.3 C
+0.49 C
1929
7.5 C
-1.37 C
1930
9.5 C
+0.69 C
1931
11.7 C
+2.85 C
1932
8.8 C
-0.06 C
1933
10.0 C
+1.17 C
1934
10.3 C
+1.42 C
1935
8.8 C
-0.08 C
1936
8.6 C
-0.22 C
1937
8.2 C
-0.67 C
1938
10.3 C
+1.44 C
1939
10.3 C
+1.47 C
1940
8.6 C
-0.26 C
1941
10.2 C
+1.41 C
1942
8.7 C
-0.10 C
1943
8.2 C
-0.60 C
1944
9.2 C
+0.34 C
1945
8.3 C
-0.55 C
1946
9.7 C
+0.83 C
1947
8.9 C
+0.04 C
1948
9.1 C
+0.25 C
1949
9.0 C
+0.15 C
The annual mean temperature here has risen by 0.20 C (0.04 to 0.36) per decade over 1896 to 1949. In Fahrenheit: 0.4 F (0.1 to 0.6) per decade. The slope is a straight line fitted to 54 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Waterloo
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.20 C (0.04 to 0.36) per decade
0.4 F (0.1 to 0.6) per decade
1896 to 1949
54
Rise
Mean daily maximum
0.14 C (-0.03 to 0.32) per decade
0.3 F (-0.1 to 0.6) per decade
1896 to 1949
54
Not clearly different from zero
Mean daily minimum
0.3 C (0.1 to 0.4) per decade
0.5 F (0.2 to 0.7) per decade
1896 to 1949
54
Rise
A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.
Extremes by Year
1895 to 1950
Yearly extremes at Waterloo: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
44.4 C (111.9 F)
1936
37.2 C (99.0 F)
56
Coldest night (TNn)
-36.1 C (-33.0 F)
1930
-28.9 C (-20.0 F)
56
Wettest day (Rx1day)
133.4 mm (5.3 in)
1942
47.1 mm (1.9 in)
56
Wettest five days (Rx5day)
176.0 mm (6.9 in)
1942
61.5 mm (2.4 in)
56
Longest dry spell (CDD)
34 days
1947
21 days
56
Hottest day (TXx)
The hottest day of the year at Waterloo, 1895 to 1950. The record is 44.4 C (111.9 F) in 1936, marked on the chart; the median year is 37.2 C (99.0 F).
Hottest day (TXx) at Waterloo by year
Year
Hottest day (TXx)
1895
37.8 C (100.0 F)
1896
36.1 C (97.0 F)
1897
37.8 C (100.0 F)
1898
36.1 C (97.0 F)
1899
36.1 C (97.0 F)
1900
35.0 C (95.0 F)
1901
41.7 C (107.1 F)
1902
34.4 C (93.9 F)
1903
35.0 C (95.0 F)
1904
36.7 C (98.1 F)
1905
37.2 C (99.0 F)
1906
35.0 C (95.0 F)
1907
35.0 C (95.0 F)
1908
37.2 C (99.0 F)
1909
36.7 C (98.1 F)
1910
37.2 C (99.0 F)
1911
42.8 C (109.0 F)
1912
36.1 C (97.0 F)
1913
37.8 C (100.0 F)
1914
38.3 C (100.9 F)
1915
32.2 C (90.0 F)
1916
40.0 C (104.0 F)
1917
38.9 C (102.0 F)
1918
40.0 C (104.0 F)
1919
38.3 C (100.9 F)
1920
36.1 C (97.0 F)
1921
38.3 C (100.9 F)
1922
38.9 C (102.0 F)
1923
38.3 C (100.9 F)
1924
35.6 C (96.1 F)
1925
38.3 C (100.9 F)
1926
39.4 C (102.9 F)
1927
37.8 C (100.0 F)
1928
35.0 C (95.0 F)
1929
35.0 C (95.0 F)
1930
40.6 C (105.1 F)
1931
41.1 C (106.0 F)
1932
37.2 C (99.0 F)
1933
39.4 C (102.9 F)
1934
42.2 C (108.0 F)
1935
37.8 C (100.0 F)
1936
44.4 C (111.9 F)
1937
40.6 C (105.1 F)
1938
36.7 C (98.1 F)
1939
38.9 C (102.0 F)
1940
40.0 C (104.0 F)
1941
36.7 C (98.1 F)
1942
35.0 C (95.0 F)
1943
37.2 C (99.0 F)
1944
34.4 C (93.9 F)
1945
35.0 C (95.0 F)
1946
34.4 C (93.9 F)
1947
36.7 C (98.1 F)
1948
37.2 C (99.0 F)
1949
34.4 C (93.9 F)
1950
7.8 C (46.0 F)
Coldest night (TNn)
The coldest night of the year at Waterloo, 1895 to 1950. The record is -36.1 C (-33.0 F) in 1930, marked on the chart; the median year is -28.9 C (-20.0 F).
Coldest night (TNn) at Waterloo by year
Year
Coldest night (TNn)
1895
-31.1 C (-24.0 F)
1896
-25.6 C (-14.1 F)
1897
-30.0 C (-22.0 F)
1898
-26.1 C (-15.0 F)
1899
-32.8 C (-27.0 F)
1900
-24.4 C (-11.9 F)
1901
-29.4 C (-20.9 F)
1902
-30.6 C (-23.1 F)
1903
-26.7 C (-16.1 F)
1904
-31.7 C (-25.1 F)
1905
-32.8 C (-27.0 F)
1906
-27.2 C (-17.0 F)
1907
-27.8 C (-18.0 F)
1908
-23.3 C (-9.9 F)
1909
-28.9 C (-20.0 F)
1910
-31.7 C (-25.1 F)
1911
-27.8 C (-18.0 F)
1912
-35.6 C (-32.1 F)
1913
-25.0 C (-13.0 F)
1914
-33.3 C (-27.9 F)
1915
-33.9 C (-29.0 F)
1916
-32.2 C (-26.0 F)
1917
-31.7 C (-25.1 F)
1918
-34.4 C (-29.9 F)
1919
-33.9 C (-29.0 F)
1920
-26.1 C (-15.0 F)
1921
-25.6 C (-14.1 F)
1922
-28.9 C (-20.0 F)
1923
-27.2 C (-17.0 F)
1924
-32.2 C (-26.0 F)
1925
-30.6 C (-23.1 F)
1926
-26.1 C (-15.0 F)
1927
-25.0 C (-13.0 F)
1928
-27.2 C (-17.0 F)
1929
-31.7 C (-25.1 F)
1930
-36.1 C (-33.0 F)
1931
-23.9 C (-11.0 F)
1932
-28.9 C (-20.0 F)
1933
-33.3 C (-27.9 F)
1934
-25.0 C (-13.0 F)
1935
-30.6 C (-23.1 F)
1936
-33.9 C (-29.0 F)
1937
-27.2 C (-17.0 F)
1938
-25.6 C (-14.1 F)
1939
-22.8 C (-9.0 F)
1940
-28.9 C (-20.0 F)
1941
-24.4 C (-11.9 F)
1942
-32.2 C (-26.0 F)
1943
-30.0 C (-22.0 F)
1944
-27.8 C (-18.0 F)
1945
-26.1 C (-15.0 F)
1946
-26.7 C (-16.1 F)
1947
-29.4 C (-20.9 F)
1948
-27.8 C (-18.0 F)
1949
-28.9 C (-20.0 F)
1950
-25.6 C (-14.1 F)
Wettest day (Rx1day)
The wettest day of the year at Waterloo, 1895 to 1950. The record is 133.4 mm (5.3 in) in 1942, marked on the chart; the median year is 47.1 mm (1.9 in).
Wettest day (Rx1day) at Waterloo by year
Year
Wettest day (Rx1day)
1895
31.2 mm (1.2 in)
1896
49.5 mm (1.9 in)
1897
39.4 mm (1.6 in)
1898
54.6 mm (2.1 in)
1899
70.1 mm (2.8 in)
1900
59.7 mm (2.4 in)
1901
23.6 mm (0.9 in)
1902
82.8 mm (3.3 in)
1903
70.6 mm (2.8 in)
1904
58.7 mm (2.3 in)
1905
61.7 mm (2.4 in)
1906
45.0 mm (1.8 in)
1907
39.1 mm (1.5 in)
1908
34.3 mm (1.4 in)
1909
60.5 mm (2.4 in)
1910
43.4 mm (1.7 in)
1911
34.5 mm (1.4 in)
1912
101.6 mm (4.0 in)
1913
50.8 mm (2.0 in)
1914
40.6 mm (1.6 in)
1915
101.6 mm (4.0 in)
1916
30.5 mm (1.2 in)
1917
43.9 mm (1.7 in)
1918
41.9 mm (1.6 in)
1919
114.3 mm (4.5 in)
1920
35.1 mm (1.4 in)
1921
50.8 mm (2.0 in)
1922
40.9 mm (1.6 in)
1923
37.3 mm (1.5 in)
1924
39.4 mm (1.6 in)
1925
47.2 mm (1.9 in)
1926
42.2 mm (1.7 in)
1927
40.9 mm (1.6 in)
1928
91.4 mm (3.6 in)
1929
31.0 mm (1.2 in)
1930
49.0 mm (1.9 in)
1931
58.7 mm (2.3 in)
1932
28.2 mm (1.1 in)
1933
47.0 mm (1.9 in)
1934
41.9 mm (1.6 in)
1935
50.8 mm (2.0 in)
1936
58.4 mm (2.3 in)
1937
34.5 mm (1.4 in)
1938
64.8 mm (2.6 in)
1939
19.6 mm (0.8 in)
1940
49.5 mm (1.9 in)
1941
47.8 mm (1.9 in)
1942
133.4 mm (5.3 in)
1943
33.8 mm (1.3 in)
1944
34.8 mm (1.4 in)
1945
29.7 mm (1.2 in)
1946
55.1 mm (2.2 in)
1947
100.3 mm (3.9 in)
1948
78.0 mm (3.1 in)
1949
48.3 mm (1.9 in)
1950
19.1 mm (0.8 in)
Wettest five days (Rx5day)
The wettest five days of the year at Waterloo, 1895 to 1950. The record is 176.0 mm (6.9 in) in 1942, marked on the chart; the median year is 61.5 mm (2.4 in).
Wettest five days (Rx5day) at Waterloo by year
Year
Wettest five days (Rx5day)
1895
69.6 mm (2.7 in)
1896
56.9 mm (2.2 in)
1897
39.4 mm (1.6 in)
1898
57.6 mm (2.3 in)
1899
96.3 mm (3.8 in)
1900
78.8 mm (3.1 in)
1901
18.8 mm (0.7 in)
1902
100.6 mm (4.0 in)
1903
105.4 mm (4.1 in)
1904
78.5 mm (3.1 in)
1905
70.2 mm (2.8 in)
1906
50.6 mm (2.0 in)
1907
65.2 mm (2.6 in)
1908
68.3 mm (2.7 in)
1909
35.6 mm (1.4 in)
1910
17.5 mm (0.7 in)
1911
46.3 mm (1.8 in)
1912
102.4 mm (4.0 in)
1913
64.0 mm (2.5 in)
1914
60.0 mm (2.4 in)
1915
115.9 mm (4.6 in)
1916
32.0 mm (1.3 in)
1917
112.5 mm (4.4 in)
1918
71.1 mm (2.8 in)
1919
66.5 mm (2.6 in)
1920
48.8 mm (1.9 in)
1921
51.4 mm (2.0 in)
1922
63.0 mm (2.5 in)
1923
46.0 mm (1.8 in)
1924
12.7 mm (0.5 in)
1925
42.2 mm (1.7 in)
1926
59.0 mm (2.3 in)
1927
87.1 mm (3.4 in)
1928
33.0 mm (1.3 in)
1929
31.0 mm (1.2 in)
1930
49.3 mm (1.9 in)
1931
91.8 mm (3.6 in)
1932
28.2 mm (1.1 in)
1933
107.0 mm (4.2 in)
1934
48.6 mm (1.9 in)
1935
83.7 mm (3.3 in)
1936
89.6 mm (3.5 in)
1937
47.0 mm (1.9 in)
1938
58.2 mm (2.3 in)
1939
30.8 mm (1.2 in)
1940
44.5 mm (1.8 in)
1941
79.0 mm (3.1 in)
1942
176.0 mm (6.9 in)
1943
33.8 mm (1.3 in)
1944
66.1 mm (2.6 in)
1945
47.6 mm (1.9 in)
1946
81.5 mm (3.2 in)
1947
69.9 mm (2.8 in)
1948
81.1 mm (3.2 in)
1949
64.8 mm (2.6 in)
1950
21.1 mm (0.8 in)
Longest dry spell (CDD)
The longest dry spell of the year at Waterloo, 1895 to 1950. The record is 34 days in 1947, marked on the chart; the median year is 21 days.
Longest dry spell (CDD) at Waterloo by year
Year
Longest dry spell (CDD)
1895
15 days
1896
23 days
1897
22 days
1898
15 days
1899
14 days
1900
17 days
1901
19 days
1902
18 days
1903
20 days
1904
21 days
1905
21 days
1906
27 days
1907
14 days
1908
24 days
1909
12 days
1910
29 days
1911
13 days
1912
20 days
1913
20 days
1914
30 days
1915
18 days
1916
29 days
1917
18 days
1918
21 days
1919
27 days
1920
15 days
1921
13 days
1922
18 days
1923
19 days
1924
17 days
1925
21 days
1926
16 days
1927
19 days
1928
18 days
1929
24 days
1930
24 days
1931
31 days
1932
22 days
1933
25 days
1934
26 days
1935
24 days
1936
22 days
1937
18 days
1938
18 days
1939
24 days
1940
16 days
1941
13 days
1942
29 days
1943
27 days
1944
23 days
1945
21 days
1946
27 days
1947
34 days
1948
33 days
1949
29 days
1950
11 days
Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.
Frost Dates and Growing Season
54 years with a frost
Across 54 years with a frost, the median last spring frost at Waterloo falls on 3 May and the median first autumn frost on 4 October, which leaves a median of 155 days between them.
Fitted over all years, the growing season changes by +0.2 days per decade at this station.
Frost dates and growing season at Waterloo
Measure
Median, all years
Earliest period
Recent period (1920 to 1949)
Recent against earliest
Fitted trend
Last spring frost
3 May
n/a
3 May
n/a
+0.2 days per decade
First autumn frost
4 October
n/a
1 October
n/a
+0.4 days per decade
Growing days
155 days
n/a
154 days
n/a
+0.2 days per decade
A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.
Station Changes
1 suspected
One change was suspected in the annual mean temperature of Waterloo, at 1912. Each is measured against neighbouring stations.
Relative to 5 neighbouring stations, the station's annual mean temperature from 1912 ran 0.3 C (0.5 F) lower than in the years before (likely change).
Suspected changes in the annual mean temperature at Waterloo, against neighbouring stations
Year
Shift (C)
Shift (F)
Strength
Neighbours
1912
-0.3
-0.5
likely
5
Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.
Download the Data
Data for Waterloo standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Waterloo threshold days by year: CSV or JSON. Field meanings are on the data page.
Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-14 (14 October 2026). Records are computed by this site and are not official.