Record envelope, standing records and threshold days for Grass Valley (USC00043571), California, United States, with 74 years of record.
Key Facts for Grass Valley
Grass Valley (USC00043571) is a weather station in California, United States at 39.22 latitude and -121.07 longitude, 805 m (2,641 ft) above sea level.
The station reports from 1893 to 1966, 74 years of record.
1,464 records set at Grass Valley still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
Grass Valley set a daily record high maximum temperature of 36.1 C (97.0 F) on 30 September 1966.
About the Station
Location: California, United States, 39.22 latitude, -121.07 longitude.
Elevation: 805 m (2,641 ft).
Period of record: 1893 to 1966, 74 years.
Eligible elements: tmax, tmin, prcp.
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 Grass Valley. 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 Grass Valley, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
26.1 C (79.0 F)
-12.2 C (10.0 F)
n/a
n/a
Feb
30.0 C (86.0 F)
-12.2 C (10.0 F)
n/a
n/a
Mar
33.3 C (91.9 F)
-7.2 C (19.0 F)
n/a
n/a
Apr
32.8 C (91.0 F)
-6.7 C (19.9 F)
n/a
n/a
May
36.7 C (98.1 F)
-5.6 C (21.9 F)
n/a
n/a
Jun
41.1 C (106.0 F)
-2.2 C (28.0 F)
n/a
n/a
Jul
42.2 C (108.0 F)
1.7 C (35.1 F)
n/a
n/a
Aug
43.9 C (111.0 F)
5.0 C (41.0 F)
n/a
n/a
Sep
41.7 C (107.1 F)
-3.9 C (25.0 F)
n/a
n/a
Oct
37.8 C (100.0 F)
-3.9 C (25.0 F)
n/a
n/a
Nov
32.2 C (90.0 F)
-7.2 C (19.0 F)
n/a
n/a
Dec
31.1 C (88.0 F)
-10.6 C (12.9 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Grass Valley still stand. 1906 holds the most, with 83.
Standing records at Grass Valley by the year they were set
Year set
Standing records
1905
26
1906
83
1907
22
1908
3
1909
22
1910
17
1911
33
1912
25
1913
38
1914
18
1915
10
1916
43
1917
25
1918
24
1919
23
1920
29
1921
15
1922
23
1923
18
1924
44
1925
55
1926
25
1927
18
1928
17
1929
27
1930
20
1931
61
1932
25
1933
31
1934
49
1935
24
1936
34
1937
11
1938
14
1939
15
1940
8
1941
8
1942
13
1943
24
1944
20
1945
18
1946
13
1947
22
1948
31
1949
21
1950
19
1951
12
1952
13
1953
12
1954
31
1955
49
1956
7
1957
9
1958
15
1959
15
1960
17
1961
23
1962
16
1963
16
1964
25
1965
14
1966
26
All-Time Record Progression
1 new records
1 all-time records were set at Grass Valley between 22 January 1962 and 22 January 1962. Each dot is a new record.
When Grass Valley set new all-time records
Date
Kind
Detail
1962-01-22
Record low minimum temperature
Record low minimum temperature -12.2 C (10.0 F)
Wettest Day of Each Month
Dec: 205.7 mm (8.1 in)
The wettest day on record for each calendar month at Grass Valley. The most was 205.7 mm (8.1 in) on 31 December 1913.
Record daily precipitation for each month at Grass Valley
Month
Record daily precipitation (mm)
Date
Jan
161.3 mm (6.4 in)
14 January 1909
Feb
186.9 mm (7.4 in)
8 February 1960
Mar
121.7 mm (4.8 in)
30 March 1940
Apr
95.3 mm (3.8 in)
30 April 1901
May
113.8 mm (4.5 in)
18 May 1957
Jun
57.9 mm (2.3 in)
15 June 1929
Jul
16.8 mm (0.7 in)
1 July 1916
Aug
19.6 mm (0.8 in)
12 August 1965
Sep
58.9 mm (2.3 in)
19 September 1959
Oct
157.5 mm (6.2 in)
13 October 1962
Nov
149.6 mm (5.9 in)
18 November 1950
Dec
205.7 mm (8.1 in)
31 December 1913
Period of Record Coverage
1905 to 1966
Complete yearUnder 90 percent of days
62 years of record at Grass Valley, 1905 to 1966. 5 years have data for under 90 percent of days and are left out of rankings: 1905, 1907, 1908, 1946, 1966.
Cooler than the station meanWarmer than the station mean
One stripe for each of 55 complete years at Grass Valley, 1906 to 1965. Blue stripes are years cooler than the station's own mean of 14.6 C (58.3 F); red stripes are warmer. The coolest year was 1906, at 11.8 C (53.2 F), and the warmest was 1934, at 17.9 C (64.1 F). The strongest colour marks a difference of 3.3 C (5.9 F).
Annual mean temperature at Grass Valley as warming stripes, 1906 to 1965
Year
Annual mean temperature
Difference from the station mean
1906
11.8 C
-2.84 C
1909
12.8 C
-1.84 C
1910
13.9 C
-0.73 C
1911
12.3 C
-2.37 C
1912
12.2 C
-2.45 C
1913
13.3 C
-1.33 C
1914
13.9 C
-0.76 C
1915
13.4 C
-1.20 C
1916
13.0 C
-1.64 C
1917
14.6 C
-0.02 C
1918
14.0 C
-0.66 C
1919
13.8 C
-0.84 C
1920
13.3 C
-1.32 C
1921
14.1 C
-0.52 C
1922
13.6 C
-1.08 C
1923
15.1 C
+0.48 C
1924
16.3 C
+1.68 C
1925
15.8 C
+1.17 C
1926
16.7 C
+2.08 C
1927
15.5 C
+0.85 C
1928
16.2 C
+1.60 C
1929
16.2 C
+1.55 C
1930
15.7 C
+1.09 C
1931
16.8 C
+2.15 C
1932
16.3 C
+1.62 C
1933
16.2 C
+1.53 C
1934
17.9 C
+3.23 C
1935
16.0 C
+1.35 C
1936
17.2 C
+2.52 C
1937
15.6 C
+1.01 C
1938
15.1 C
+0.50 C
1939
16.5 C
+1.86 C
1940
15.9 C
+1.28 C
1941
14.8 C
+0.18 C
1942
14.7 C
+0.04 C
1943
15.5 C
+0.91 C
1944
15.4 C
+0.74 C
1947
14.4 C
-0.19 C
1948
12.9 C
-1.72 C
1949
13.8 C
-0.80 C
1950
14.7 C
+0.07 C
1951
14.6 C
-0.01 C
1952
14.3 C
-0.31 C
1953
14.5 C
-0.10 C
1954
13.7 C
-0.90 C
1955
13.2 C
-1.39 C
1956
14.4 C
-0.22 C
1957
13.8 C
-0.86 C
1958
14.9 C
+0.23 C
1959
15.3 C
+0.62 C
1960
14.2 C
-0.47 C
1961
13.8 C
-0.85 C
1962
13.9 C
-0.72 C
1963
13.6 C
-1.05 C
1965
13.7 C
-0.95 C
The fitted trend in annual mean temperature here over 1906 to 1965 is 0.1 C (-0.1 to 0.3) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.2 F (-0.2 to 0.6) per decade. The slope is a straight line fitted to 55 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Grass Valley
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.1 C (-0.1 to 0.3) per decade
0.2 F (-0.2 to 0.6) per decade
1906 to 1965
55
Not clearly different from zero
Mean daily maximum
0.24 C (0.03 to 0.45) per decade
0.4 F (0.1 to 0.8) per decade
1906 to 1965
55
Rise
Mean daily minimum
-0.04 C (-0.30 to 0.22) per decade
-0.1 F (-0.5 to 0.4) per decade
1906 to 1965
55
Not clearly different from zero
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
1893 to 1966
Yearly extremes at Grass Valley: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
43.9 C (111.0 F)
1933
38.9 C (102.0 F)
62
Coldest night (TNn)
-12.2 C (10.0 F)
1962
-6.7 C (19.9 F)
62
Wettest day (Rx1day)
205.7 mm (8.1 in)
1913
95.3 mm (3.8 in)
72
Wettest five days (Rx5day)
540.1 mm (21.3 in)
1955
213.4 mm (8.4 in)
72
Longest dry spell (CDD)
133 days
1902
73 days
72
Hottest day (TXx)
The hottest day of the year at Grass Valley, 1893 to 1966. The record is 43.9 C (111.0 F) in 1933, marked on the chart; the median year is 38.9 C (102.0 F).
Hottest day (TXx) at Grass Valley by year
Year
Hottest day (TXx)
1893
n/a
1894
n/a
1895
n/a
1896
n/a
1897
n/a
1898
n/a
1899
n/a
1900
n/a
1901
n/a
1902
n/a
1905
32.2 C (90.0 F)
1906
35.6 C (96.1 F)
1907
30.0 C (86.0 F)
1908
16.1 C (61.0 F)
1909
34.4 C (93.9 F)
1910
37.2 C (99.0 F)
1911
37.8 C (100.0 F)
1912
34.4 C (93.9 F)
1913
38.9 C (102.0 F)
1914
36.1 C (97.0 F)
1915
36.7 C (98.1 F)
1916
35.6 C (96.1 F)
1917
36.7 C (98.1 F)
1918
36.7 C (98.1 F)
1919
36.7 C (98.1 F)
1920
38.3 C (100.9 F)
1921
37.2 C (99.0 F)
1922
38.9 C (102.0 F)
1923
41.1 C (106.0 F)
1924
40.6 C (105.1 F)
1925
42.2 C (108.0 F)
1926
41.1 C (106.0 F)
1927
39.4 C (102.9 F)
1928
40.0 C (104.0 F)
1929
40.6 C (105.1 F)
1930
38.9 C (102.0 F)
1931
41.1 C (106.0 F)
1932
40.0 C (104.0 F)
1933
43.9 C (111.0 F)
1934
41.1 C (106.0 F)
1935
41.1 C (106.0 F)
1936
40.0 C (104.0 F)
1937
40.0 C (104.0 F)
1938
39.4 C (102.9 F)
1939
40.0 C (104.0 F)
1940
39.4 C (102.9 F)
1941
38.9 C (102.0 F)
1942
41.1 C (106.0 F)
1943
38.9 C (102.0 F)
1944
40.0 C (104.0 F)
1945
41.7 C (107.1 F)
1946
40.6 C (105.1 F)
1947
37.2 C (99.0 F)
1948
38.9 C (102.0 F)
1949
37.2 C (99.0 F)
1950
41.1 C (106.0 F)
1951
38.3 C (100.9 F)
1952
37.2 C (99.0 F)
1953
38.9 C (102.0 F)
1954
37.8 C (100.0 F)
1955
40.6 C (105.1 F)
1956
37.8 C (100.0 F)
1957
37.8 C (100.0 F)
1958
37.8 C (100.0 F)
1959
38.9 C (102.0 F)
1960
40.6 C (105.1 F)
1961
39.4 C (102.9 F)
1962
37.8 C (100.0 F)
1963
38.9 C (102.0 F)
1964
38.9 C (102.0 F)
1965
37.8 C (100.0 F)
1966
40.0 C (104.0 F)
Coldest night (TNn)
The coldest night of the year at Grass Valley, 1893 to 1966. The record is -12.2 C (10.0 F) in 1962, marked on the chart; the median year is -6.7 C (19.9 F).
Coldest night (TNn) at Grass Valley by year
Year
Coldest night (TNn)
1893
n/a
1894
n/a
1895
n/a
1896
n/a
1897
n/a
1898
n/a
1899
n/a
1900
n/a
1901
n/a
1902
n/a
1905
-4.4 C (24.1 F)
1906
-6.7 C (19.9 F)
1907
-6.7 C (19.9 F)
1908
-7.2 C (19.0 F)
1909
-7.8 C (18.0 F)
1910
-11.1 C (12.0 F)
1911
-8.9 C (16.0 F)
1912
-8.9 C (16.0 F)
1913
-11.7 C (10.9 F)
1914
-4.4 C (24.1 F)
1915
-6.1 C (21.0 F)
1916
-9.4 C (15.1 F)
1917
-7.2 C (19.0 F)
1918
-6.7 C (19.9 F)
1919
-5.6 C (21.9 F)
1920
-6.7 C (19.9 F)
1921
-5.6 C (21.9 F)
1922
-9.4 C (15.1 F)
1923
-5.6 C (21.9 F)
1924
-7.8 C (18.0 F)
1925
-1.1 C (30.0 F)
1926
-3.3 C (26.1 F)
1927
-2.2 C (28.0 F)
1928
-4.4 C (24.1 F)
1929
-7.2 C (19.0 F)
1930
-7.2 C (19.0 F)
1931
-3.9 C (25.0 F)
1932
-10.6 C (12.9 F)
1933
-5.0 C (23.0 F)
1934
-1.1 C (30.0 F)
1935
-5.6 C (21.9 F)
1936
-1.1 C (30.0 F)
1937
-11.1 C (12.0 F)
1938
-4.4 C (24.1 F)
1939
-5.6 C (21.9 F)
1940
-2.8 C (27.0 F)
1941
-2.8 C (27.0 F)
1942
-3.9 C (25.0 F)
1943
-5.6 C (21.9 F)
1944
-3.3 C (26.1 F)
1945
-3.9 C (25.0 F)
1946
-7.8 C (18.0 F)
1947
-6.7 C (19.9 F)
1948
-7.8 C (18.0 F)
1949
-11.1 C (12.0 F)
1950
-10.0 C (14.0 F)
1951
-6.7 C (19.9 F)
1952
-6.7 C (19.9 F)
1953
-7.2 C (19.0 F)
1954
-8.9 C (16.0 F)
1955
-8.9 C (16.0 F)
1956
-7.2 C (19.0 F)
1957
-6.7 C (19.9 F)
1958
-6.1 C (21.0 F)
1959
-5.0 C (23.0 F)
1960
-7.2 C (19.0 F)
1961
-7.2 C (19.0 F)
1962
-12.2 C (10.0 F)
1963
-7.8 C (18.0 F)
1964
-6.1 C (21.0 F)
1965
-8.9 C (16.0 F)
1966
-7.2 C (19.0 F)
Wettest day (Rx1day)
The wettest day of the year at Grass Valley, 1893 to 1966. The record is 205.7 mm (8.1 in) in 1913, marked on the chart; the median year is 95.3 mm (3.8 in).
Wettest day (Rx1day) at Grass Valley by year
Year
Wettest day (Rx1day)
1893
71.9 mm (2.8 in)
1894
134.1 mm (5.3 in)
1895
160.3 mm (6.3 in)
1896
93.5 mm (3.7 in)
1897
116.8 mm (4.6 in)
1898
52.3 mm (2.1 in)
1899
115.3 mm (4.5 in)
1900
121.2 mm (4.8 in)
1901
110.2 mm (4.3 in)
1902
70.1 mm (2.8 in)
1905
31.2 mm (1.2 in)
1906
141.0 mm (5.6 in)
1907
124.5 mm (4.9 in)
1908
36.1 mm (1.4 in)
1909
161.3 mm (6.4 in)
1910
61.2 mm (2.4 in)
1911
122.4 mm (4.8 in)
1912
112.3 mm (4.4 in)
1913
205.7 mm (8.1 in)
1914
77.0 mm (3.0 in)
1915
149.9 mm (5.9 in)
1916
143.5 mm (5.6 in)
1917
90.9 mm (3.6 in)
1918
74.9 mm (2.9 in)
1919
93.7 mm (3.7 in)
1920
94.5 mm (3.7 in)
1921
75.2 mm (3.0 in)
1922
102.9 mm (4.1 in)
1923
52.8 mm (2.1 in)
1924
76.2 mm (3.0 in)
1925
101.6 mm (4.0 in)
1926
108.7 mm (4.3 in)
1927
91.4 mm (3.6 in)
1928
95.3 mm (3.8 in)
1929
99.1 mm (3.9 in)
1930
109.7 mm (4.3 in)
1931
77.5 mm (3.1 in)
1932
66.0 mm (2.6 in)
1933
94.7 mm (3.7 in)
1934
79.2 mm (3.1 in)
1935
72.6 mm (2.9 in)
1936
84.6 mm (3.3 in)
1937
149.4 mm (5.9 in)
1938
70.4 mm (2.8 in)
1939
93.5 mm (3.7 in)
1940
124.7 mm (4.9 in)
1941
81.0 mm (3.2 in)
1942
113.3 mm (4.5 in)
1943
118.6 mm (4.7 in)
1944
96.3 mm (3.8 in)
1945
104.6 mm (4.1 in)
1946
130.8 mm (5.1 in)
1947
120.1 mm (4.7 in)
1948
95.3 mm (3.8 in)
1949
94.7 mm (3.7 in)
1950
149.6 mm (5.9 in)
1951
95.3 mm (3.8 in)
1952
91.4 mm (3.6 in)
1953
93.2 mm (3.7 in)
1954
95.8 mm (3.8 in)
1955
165.4 mm (6.5 in)
1956
85.1 mm (3.4 in)
1957
113.8 mm (4.5 in)
1958
82.3 mm (3.2 in)
1959
78.7 mm (3.1 in)
1960
186.9 mm (7.4 in)
1961
69.3 mm (2.7 in)
1962
162.8 mm (6.4 in)
1963
120.7 mm (4.8 in)
1964
152.4 mm (6.0 in)
1965
83.8 mm (3.3 in)
1966
94.5 mm (3.7 in)
Wettest five days (Rx5day)
The wettest five days of the year at Grass Valley, 1893 to 1966. The record is 540.1 mm (21.3 in) in 1955, marked on the chart; the median year is 213.4 mm (8.4 in).
Wettest five days (Rx5day) at Grass Valley by year
Year
Wettest five days (Rx5day)
1893
157.6 mm (6.2 in)
1894
186.4 mm (7.3 in)
1895
205.7 mm (8.1 in)
1896
316.2 mm (12.4 in)
1897
239.7 mm (9.4 in)
1898
57.4 mm (2.3 in)
1899
255.8 mm (10.1 in)
1900
200.1 mm (7.9 in)
1901
202.5 mm (8.0 in)
1902
169.1 mm (6.7 in)
1905
70.8 mm (2.8 in)
1906
366.7 mm (14.4 in)
1907
313.1 mm (12.3 in)
1908
69.4 mm (2.7 in)
1909
425.7 mm (16.8 in)
1910
147.8 mm (5.8 in)
1911
334.8 mm (13.2 in)
1912
167.9 mm (6.6 in)
1913
269.2 mm (10.6 in)
1914
337.5 mm (13.3 in)
1915
200.2 mm (7.9 in)
1916
248.7 mm (9.8 in)
1917
260.1 mm (10.2 in)
1918
140.7 mm (5.5 in)
1919
286.2 mm (11.3 in)
1920
143.5 mm (5.6 in)
1921
194.3 mm (7.6 in)
1922
249.2 mm (9.8 in)
1923
172.0 mm (6.8 in)
1924
132.3 mm (5.2 in)
1925
257.2 mm (10.1 in)
1926
239.7 mm (9.4 in)
1927
216.0 mm (8.5 in)
1928
342.5 mm (13.5 in)
1929
316.9 mm (12.5 in)
1930
167.0 mm (6.6 in)
1931
227.9 mm (9.0 in)
1932
158.2 mm (6.2 in)
1933
147.3 mm (5.8 in)
1934
176.2 mm (6.9 in)
1935
143.5 mm (5.6 in)
1936
294.7 mm (11.6 in)
1937
273.8 mm (10.8 in)
1938
226.3 mm (8.9 in)
1939
163.4 mm (6.4 in)
1940
309.7 mm (12.2 in)
1941
210.8 mm (8.3 in)
1942
218.1 mm (8.6 in)
1943
276.8 mm (10.9 in)
1944
181.9 mm (7.2 in)
1945
273.4 mm (10.8 in)
1946
218.9 mm (8.6 in)
1947
137.3 mm (5.4 in)
1948
157.3 mm (6.2 in)
1949
190.8 mm (7.5 in)
1950
387.3 mm (15.2 in)
1951
189.7 mm (7.5 in)
1952
266.7 mm (10.5 in)
1953
135.2 mm (5.3 in)
1954
148.4 mm (5.8 in)
1955
540.1 mm (21.3 in)
1956
168.7 mm (6.6 in)
1957
189.8 mm (7.5 in)
1958
267.4 mm (10.5 in)
1959
195.2 mm (7.7 in)
1960
269.1 mm (10.6 in)
1961
156.9 mm (6.2 in)
1962
505.9 mm (19.9 in)
1963
275.6 mm (10.9 in)
1964
430.7 mm (17.0 in)
1965
290.0 mm (11.4 in)
1966
129.1 mm (5.1 in)
Longest dry spell (CDD)
The longest dry spell of the year at Grass Valley, 1893 to 1966. The record is 133 days in 1902, marked on the chart; the median year is 73 days.
Longest dry spell (CDD) at Grass Valley by year
Year
Longest dry spell (CDD)
1893
109 days
1894
59 days
1895
54 days
1896
85 days
1897
69 days
1898
116 days
1899
66 days
1900
115 days
1901
22 days
1902
133 days
1905
52 days
1906
64 days
1907
31 days
1908
20 days
1909
59 days
1910
127 days
1911
109 days
1912
44 days
1913
61 days
1914
62 days
1915
22 days
1916
60 days
1917
31 days
1918
42 days
1919
33 days
1920
54 days
1921
24 days
1922
34 days
1923
27 days
1924
31 days
1925
27 days
1926
61 days
1927
86 days
1928
93 days
1929
111 days
1930
86 days
1931
127 days
1932
129 days
1933
90 days
1934
73 days
1935
91 days
1936
87 days
1937
107 days
1938
97 days
1939
95 days
1940
92 days
1941
41 days
1942
73 days
1943
127 days
1944
126 days
1945
89 days
1946
57 days
1947
118 days
1948
116 days
1949
99 days
1950
69 days
1951
125 days
1952
61 days
1953
119 days
1954
77 days
1955
73 days
1956
110 days
1957
110 days
1958
65 days
1959
110 days
1960
79 days
1961
65 days
1962
84 days
1963
68 days
1964
41 days
1965
53 days
1966
83 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
53 years with a frost
Across 53 years with a frost, the median last spring frost at Grass Valley falls on 17 April and the median first autumn frost on 12 November, which leaves a median of 207 days between them.
Fitted over all years, the growing season changes by +3.6 days per decade at this station.
Frost dates and growing season at Grass Valley
Measure
Median, all years
Earliest period
Recent period (1932 to 1965)
Recent against earliest
Fitted trend
Last spring frost
17 April
n/a
15 April
n/a
-1.4 days per decade
First autumn frost
12 November
n/a
15 November
n/a
+2.2 days per decade
Growing days
207 days
n/a
215 days
n/a
+3.6 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.
Rainfall Return Levels
54 years, 1893 to 1965
A day with at least 102.9 mm (4.1 in) of rain is expected about once in 2 years. A day with at least 213.3 mm (8.4 in) of rain is expected about once in 100 years.
Rainfall return levels at Grass Valley: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
102.9 mm (4.1 in)
5 years
132.1 mm (5.2 in)
10 years
151.5 mm (6.0 in)
25 years
176.3 mm (6.9 in)
50 years
194.8 mm (7.7 in)
100 years
213.3 mm (8.4 in)
Longer than the 54 years of record
The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 54 years of values from 1893 to 1965.
A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.
The largest wettest-day totals in the fit: 205.7 mm (8.1 in) in 1913; 186.9 mm (7.4 in) in 1960; 165.4 mm (6.5 in) in 1955.
Station Changes
1 suspected
One change was suspected in the annual mean temperature of Grass Valley, at 1947. Each is measured against neighbouring stations.
Relative to 5 neighbouring stations, the station's annual mean temperature from 1947 ran 0.7 C (1.3 F) lower than in the years before (possible change).
Suspected changes in the annual mean temperature at Grass Valley, against neighbouring stations
Year
Shift (C)
Shift (F)
Strength
Neighbours
1947
-0.7
-1.3
possible
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 Grass Valley standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Grass Valley 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 2026-10-13 (13 October 2026). Records are computed by this site and are not official.