Ajo Well Weather Records (USC00020088)

Record envelope, standing records and threshold days for Ajo Well (USC00020088), Arizona, United States, with 36 years of record.

Key Facts for Ajo Well

Ajo Well (USC00020088) is a weather station in Arizona, United States at 32.45 latitude and -112.83 longitude, 436 m (1,430 ft) above sea level.
The station reports from 1940 to 1975, 36 years of record.
124 records set at Ajo Well still stand.
Records are tracked for prcp: an element needs 30 years of data to be eligible.
Ajo Well set a daily record precipitation of 9.4 mm (0.37 in) on 7 April 1975.

About the Station

Location: Arizona, United States, 32.45 latitude, -112.83 longitude.
Elevation: 436 m (1,430 ft).
Period of record: 1940 to 1975, 36 years.
Eligible elements: prcp.

Daily Record Envelope and 2026

0 days at or beyond a record

The band shows the record high and record low for each calendar day at Ajo Well. 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 Ajo Well, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	n/a	n/a	n/a	n/a
Feb	n/a	n/a	n/a	n/a
Mar	n/a	n/a	n/a	n/a
Apr	n/a	n/a	n/a	n/a
May	n/a	n/a	n/a	n/a
Jun	n/a	n/a	n/a	n/a
Jul	n/a	n/a	n/a	n/a
Aug	42.8 C (109.0 F)	18.9 C (66.0 F)	n/a	n/a
Sep	n/a	n/a	n/a	n/a
Oct	n/a	n/a	n/a	n/a
Nov	n/a	n/a	n/a	n/a
Dec	n/a	n/a	n/a	n/a

Which Years Hold Standing Records

124 standing records

124 records at Ajo Well still stand. 1970 holds the most, with 124.

Wettest Day of Each Month

Sep: 89.4 mm (3.5 in)

The wettest day on record for each calendar month at Ajo Well. The most was 89.4 mm (3.5 in) on 18 September 1946.

Record daily precipitation for each month at Ajo Well
Month	Record daily precipitation (mm)	Date
Jan	29.2 mm (1.1 in)	25 January 1949
Feb	27.7 mm (1.1 in)	5 February 1958
Mar	30.0 mm (1.2 in)	2 March 1941
Apr	31.5 mm (1.2 in)	12 April 1941
May	13.7 mm (0.5 in)	31 May 1972
Jun	15.2 mm (0.6 in)	7 June 1972
Jul	55.6 mm (2.2 in)	16 July 1940
Aug	73.7 mm (2.9 in)	28 August 1951
Sep	89.4 mm (3.5 in)	18 September 1946
Oct	34.0 mm (1.3 in)	5 October 1940
Nov	23.4 mm (0.9 in)	15 November 1946
Dec	34.8 mm (1.4 in)	11 December 1941

Period of Record Coverage

1970 to 1970

1 years of record at Ajo Well, 1970 to 1970. 1 years have data for under 90 percent of days and are left out of rankings: 1970.

Latest Records

Latest records at Ajo Well
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
7 April 1975	Ajo Well, US	daily rain	9.4 mm (0.37 in)	3.0 mm (0.12 in)	32 years	16 of 100 (Routine)
27 March 1975	Ajo Well, US	daily rain	3.3 mm (0.13 in)	0.3 mm (0.01 in)	1 year	3 of 100 (Routine)
11 March 1975	Ajo Well, US	daily rain	16.8 mm (0.7 in)	5.4 mm (0.21 in)	4 years	12 of 100 (Routine)
2 January 1975	Ajo Well, US	daily rain	0.8 mm (0.03 in)	0.8 mm (0.03 in)	33 years	14 of 100 (Routine)
29 December 1974	Ajo Well, US	daily rain	4.6 mm (0.18 in)	2.8 mm (0.11 in)	9 years	9 of 100 (Routine)
2 November 1974	Ajo Well, US	daily rain	9.7 mm (0.38 in)	4.1 mm (0.16 in)	15 years	14 of 100 (Routine)
23 October 1974	Ajo Well, US	monthly rain (Tie)	34.0 mm (1.3 in)	tie	34 years	5 of 100 (Routine)
13 October 1974	Ajo Well, US	daily rain	4.6 mm (0.18 in)	4.6 mm (0.18 in)	33 years	17 of 100 (Routine)
27 September 1974	Ajo Well, US	daily rain	25.4 mm (1.0 in)	25.4 mm (1.0 in)	33 years	31 of 100 (Routine)
7 July 1974	Ajo Well, US	daily rain	52.3 mm (2.1 in)	26.4 mm (1.0 in)	24 years	39 of 100 (Notable)
5 January 1974	Ajo Well, US	daily rain	6.9 mm (0.27 in)	6.1 mm (0.24 in)	0 years	13 of 100 (Routine)
23 November 1973	Ajo Well, US	daily rain	9.1 mm (0.36 in)	4.3 mm (0.17 in)	8 years	12 of 100 (Routine)
19 November 1973	Ajo Well, US	daily rain	11.7 mm (0.5 in)	5.1 mm (0.20 in)	8 years	13 of 100 (Routine)
14 August 1973	Ajo Well, US	daily rain	21.6 mm (0.9 in)	7.6 mm (0.30 in)	8 years	11 of 100 (Routine)
14 June 1973	Ajo Well, US	daily rain	1.0 mm (0.04 in)	0.2 mm (0.01 in)	18 years	8 of 100 (Routine)
29 March 1973	Ajo Well, US	daily rain	8.1 mm (0.32 in)	1.7 mm (0.07 in)	12 years	8 of 100 (Routine)
27 March 1973	Ajo Well, US	daily rain	3.0 mm (0.12 in)	0.7 mm (0.03 in)	7 years	6 of 100 (Routine)
21 March 1973	Ajo Well, US	daily rain	0.8 mm (0.03 in)	0.8 mm (0.03 in)	32 years	13 of 100 (Routine)
22 February 1973	Ajo Well, US	daily rain	12.7 mm (0.5 in)	6.1 mm (0.24 in)	32 years	20 of 100 (Routine)
5 January 1973	Ajo Well, US	daily rain	0.8 mm (0.03 in)	0.8 mm (0.03 in)	32 years	13 of 100 (Routine)

Extremes by Year

1940 to 1975

Yearly extremes at Ajo Well: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	42.8 C (109.0 F)	1970	42.8 C (109.0 F)	1
Coldest night (TNn)	18.9 C (66.0 F)	1970	18.9 C (66.0 F)	1
Wettest day (Rx1day)	89.4 mm (3.5 in)	1946	33.7 mm (1.3 in)	36
Wettest five days (Rx5day)	115.4 mm (4.5 in)	1951	45.6 mm (1.8 in)	36
Longest dry spell (CDD)	179 days	1974	95 days	36

Hottest day (TXx)

The hottest day of the year at Ajo Well, 1940 to 1975. The record is 42.8 C (109.0 F) in 1970, marked on the chart; the median year is 42.8 C (109.0 F).

Hottest day (TXx) at Ajo Well by year
Year	Hottest day (TXx)
1940	n/a
1941	n/a
1942	n/a
1943	n/a
1944	n/a
1945	n/a
1946	n/a
1947	n/a
1948	n/a
1949	n/a
1950	n/a
1951	n/a
1952	n/a
1953	n/a
1954	n/a
1955	n/a
1956	n/a
1957	n/a
1958	n/a
1959	n/a
1960	n/a
1961	n/a
1962	n/a
1963	n/a
1964	n/a
1965	n/a
1966	n/a
1967	n/a
1968	n/a
1969	n/a
1970	42.8 C (109.0 F)
1971	n/a
1972	n/a
1973	n/a
1974	n/a
1975	n/a

Coldest night (TNn)

The coldest night of the year at Ajo Well, 1940 to 1975. The record is 18.9 C (66.0 F) in 1970, marked on the chart; the median year is 18.9 C (66.0 F).

Coldest night (TNn) at Ajo Well by year
Year	Coldest night (TNn)
1940	n/a
1941	n/a
1942	n/a
1943	n/a
1944	n/a
1945	n/a
1946	n/a
1947	n/a
1948	n/a
1949	n/a
1950	n/a
1951	n/a
1952	n/a
1953	n/a
1954	n/a
1955	n/a
1956	n/a
1957	n/a
1958	n/a
1959	n/a
1960	n/a
1961	n/a
1962	n/a
1963	n/a
1964	n/a
1965	n/a
1966	n/a
1967	n/a
1968	n/a
1969	n/a
1970	18.9 C (66.0 F)
1971	n/a
1972	n/a
1973	n/a
1974	n/a
1975	n/a

Wettest day (Rx1day)

The wettest day of the year at Ajo Well, 1940 to 1975. The record is 89.4 mm (3.5 in) in 1946, marked on the chart; the median year is 33.7 mm (1.3 in).

Wettest day (Rx1day) at Ajo Well by year
Year	Wettest day (Rx1day)
1940	55.6 mm (2.2 in)
1941	34.8 mm (1.4 in)
1942	36.6 mm (1.4 in)
1943	55.4 mm (2.2 in)
1944	27.4 mm (1.1 in)
1945	36.8 mm (1.4 in)
1946	89.4 mm (3.5 in)
1947	28.4 mm (1.1 in)
1948	32.5 mm (1.3 in)
1949	29.2 mm (1.1 in)
1950	25.9 mm (1.0 in)
1951	73.7 mm (2.9 in)
1952	21.8 mm (0.9 in)
1953	21.6 mm (0.9 in)
1954	39.6 mm (1.6 in)
1955	35.3 mm (1.4 in)
1956	16.0 mm (0.6 in)
1957	22.6 mm (0.9 in)
1958	58.7 mm (2.3 in)
1959	21.3 mm (0.8 in)
1960	38.9 mm (1.5 in)
1961	39.9 mm (1.6 in)
1962	24.9 mm (1.0 in)
1963	17.3 mm (0.7 in)
1964	41.1 mm (1.6 in)
1965	38.4 mm (1.5 in)
1966	24.6 mm (1.0 in)
1967	53.1 mm (2.1 in)
1968	35.1 mm (1.4 in)
1969	30.0 mm (1.2 in)
1970	18.8 mm (0.7 in)
1971	68.8 mm (2.7 in)
1972	32.0 mm (1.3 in)
1973	24.6 mm (1.0 in)
1974	52.3 mm (2.1 in)
1975	16.8 mm (0.7 in)

Wettest five days (Rx5day)

The wettest five days of the year at Ajo Well, 1940 to 1975. The record is 115.4 mm (4.5 in) in 1951, marked on the chart; the median year is 45.6 mm (1.8 in).

Wettest five days (Rx5day) at Ajo Well by year
Year	Wettest five days (Rx5day)
1940	52.3 mm (2.1 in)
1941	46.0 mm (1.8 in)
1942	43.0 mm (1.7 in)
1943	96.8 mm (3.8 in)
1944	38.1 mm (1.5 in)
1945	53.3 mm (2.1 in)
1946	111.2 mm (4.4 in)
1947	60.5 mm (2.4 in)
1948	53.1 mm (2.1 in)
1949	45.2 mm (1.8 in)
1950	45.2 mm (1.8 in)
1951	115.4 mm (4.5 in)
1952	34.2 mm (1.3 in)
1953	55.1 mm (2.2 in)
1954	41.1 mm (1.6 in)
1955	50.6 mm (2.0 in)
1956	22.1 mm (0.9 in)
1957	36.1 mm (1.4 in)
1958	62.0 mm (2.4 in)
1959	40.9 mm (1.6 in)
1960	38.9 mm (1.5 in)
1961	64.0 mm (2.5 in)
1962	32.5 mm (1.3 in)
1963	24.9 mm (1.0 in)
1964	50.3 mm (2.0 in)
1965	64.5 mm (2.5 in)
1966	41.3 mm (1.6 in)
1967	53.6 mm (2.1 in)
1968	51.5 mm (2.0 in)
1969	30.0 mm (1.2 in)
1970	29.0 mm (1.1 in)
1971	70.1 mm (2.8 in)
1972	35.8 mm (1.4 in)
1973	31.7 mm (1.2 in)
1974	60.7 mm (2.4 in)
1975	26.3 mm (1.0 in)

Longest dry spell (CDD)

The longest dry spell of the year at Ajo Well, 1940 to 1975. The record is 179 days in 1974, marked on the chart; the median year is 95 days.

Longest dry spell (CDD) at Ajo Well by year
Year	Longest dry spell (CDD)
1940	150 days
1941	53 days
1942	69 days
1943	113 days
1944	72 days
1945	124 days
1946	172 days
1947	119 days
1948	125 days
1949	93 days
1950	101 days
1951	78 days
1952	68 days
1953	66 days
1954	89 days
1955	144 days
1956	147 days
1957	56 days
1958	73 days
1959	139 days
1960	77 days
1961	95 days
1962	97 days
1963	139 days
1964	110 days
1965	64 days
1966	94 days
1967	64 days
1968	92 days
1969	96 days
1970	86 days
1971	138 days
1972	151 days
1973	90 days
1974	179 days
1975	44 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.

Rainfall Return Levels

34 years, 1941 to 1974

A day with at least 32.3 mm (1.3 in) of rain is expected about once in 2 years. A day with at least 103.9 mm (4.1 in) of rain is expected about once in 100 years.

Rainfall return levels at Ajo Well: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	32.3 mm (1.3 in)
5 years	46.6 mm (1.8 in)
10 years	57.8 mm (2.3 in)
25 years	74.2 mm (2.9 in)
50 years	88.2 mm (3.5 in)	Longer than the 34 years of record
100 years	103.9 mm (4.1 in)	Longer than the 34 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, 34 years of values from 1941 to 1974.

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: 89.4 mm (3.5 in) in 1946; 73.7 mm (2.9 in) in 1951; 68.8 mm (2.7 in) in 1971.

Download the Data

Data for Ajo Well standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Ajo Well 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.

Data as of 2025-12-31. Last revised 31 December 2025 (2025-12-31).