Mertzon Weather Records (USC00415859)

Record envelope, standing records and threshold days for Mertzon (USC00415859), Texas, United States, with 47 years of record.

Key Facts for Mertzon

Mertzon (USC00415859) is a weather station in Texas, United States at 31.27 latitude and -100.82 longitude, 679 m (2,229 ft) above sea level.
The station reports from 1941 to 1987, 47 years of record.
1,464 records set at Mertzon still stand.
Records are tracked for prcp, snow, snwd: an element needs 30 years of data to be eligible.
Mertzon set a daily record precipitation of 19.1 mm (0.8 in) on 19 August 1987.

About the Station

Location: Texas, United States, 31.27 latitude, -100.82 longitude.
Elevation: 679 m (2,229 ft).
Period of record: 1941 to 1987, 47 years.
Eligible elements: prcp, snow, snwd.

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 Mertzon. 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 Mertzon, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	30.6 C (87.1 F)	-15.6 C (3.9 F)	n/a	n/a
Feb	31.7 C (89.1 F)	-15.6 C (3.9 F)	n/a	n/a
Mar	36.1 C (97.0 F)	-13.9 C (7.0 F)	n/a	n/a
Apr	37.8 C (100.0 F)	-7.2 C (19.0 F)	n/a	n/a
May	42.2 C (108.0 F)	1.1 C (34.0 F)	n/a	n/a
Jun	42.2 C (108.0 F)	4.4 C (39.9 F)	n/a	n/a
Jul	42.2 C (108.0 F)	13.3 C (55.9 F)	n/a	n/a
Aug	41.1 C (106.0 F)	12.8 C (55.0 F)	n/a	n/a
Sep	40.6 C (105.1 F)	3.3 C (37.9 F)	n/a	n/a
Oct	37.2 C (99.0 F)	-3.3 C (26.1 F)	n/a	n/a
Nov	32.8 C (91.0 F)	-14.4 C (6.1 F)	n/a	n/a
Dec	27.8 C (82.0 F)	-15.6 C (3.9 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Mertzon still stand. 1982 holds the most, with 93.

Standing records at Mertzon by the year they were set
Year set	Standing records
1963	6
1964	39
1965	61
1966	63
1967	84
1968	87
1969	61
1970	68
1971	75
1972	50
1973	46
1974	74
1975	41
1976	46
1977	49
1978	49
1979	60
1980	57
1981	46
1982	93
1983	72
1984	81
1985	60
1986	68
1987	28

All-Time Record Progression

1 new records

1 all-time records were set at Mertzon between 12 August 1971 and 12 August 1971. Each dot is a new record.

Wettest Day of Each Month

Aug: 212.1 mm (8.4 in)

The wettest day on record for each calendar month at Mertzon. The most was 212.1 mm (8.4 in) on 12 August 1971.

Record daily precipitation for each month at Mertzon
Month	Record daily precipitation (mm)	Date
Jan	39.4 mm (1.6 in)	13 January 1982
Feb	83.8 mm (3.3 in)	5 February 1987
Mar	51.3 mm (2.0 in)	8 March 1953
Apr	53.8 mm (2.1 in)	8 April 1959
May	99.1 mm (3.9 in)	10 May 1975
Jun	83.8 mm (3.3 in)	16 June 1958
Jul	104.1 mm (4.1 in)	6 July 1945
Aug	212.1 mm (8.4 in)	12 August 1971
Sep	86.4 mm (3.4 in)	6 September 1973
Oct	96.5 mm (3.8 in)	3 October 1959
Nov	50.8 mm (2.0 in)	5 November 1978
Dec	55.9 mm (2.2 in)	8 December 1980

Period of Record Coverage

1963 to 1987

25 years of record at Mertzon, 1963 to 1987. 16 years have data for under 90 percent of days and are left out of rankings: 1963, 1964, 1965, 1966, 1969, 1970, 1971, 1972 and others.

Days with data per year at Mertzon
Year	Days with data	Share of year	Complete
1963	46	13%	No
1964	287	78%	No
1965	256	70%	No
1966	273	75%	No
1967	339	93%	Yes
1968	366	100%	Yes
1969	319	87%	No
1970	292	80%	No
1971	266	73%	No
1972	255	70%	No
1973	247	68%	No
1974	312	85%	No
1975	283	78%	No
1976	252	69%	No
1977	311	85%	No
1978	276	76%	No
1979	274	75%	No
1980	340	93%	Yes
1981	353	97%	Yes
1982	340	93%	Yes
1983	345	95%	Yes
1984	331	90%	Yes
1985	352	96%	Yes
1986	360	99%	Yes
1987	195	53%	No

Latest Records

Latest records at Mertzon
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
19 August 1987	Mertzon, US	daily rain	19.1 mm (0.8 in)	11.5 mm (0.5 in)	32 years	18 of 100 (Routine)
24 July 1987	Mertzon, US	daily rain	12.7 mm (0.5 in)	2.3 mm (0.09 in)	8 years	7 of 100 (Routine)
31 May 1987	Mertzon, US	daily rain	43.2 mm (1.7 in)	24.1 mm (0.9 in)	29 years	26 of 100 (Routine)
24 May 1987	Mertzon, US	daily rain	38.1 mm (1.5 in)	7.1 mm (0.28 in)	20 years	14 of 100 (Routine)
14 May 1987	Mertzon, US	daily rain	17.8 mm (0.7 in)	13.5 mm (0.5 in)	13 years	16 of 100 (Routine)
29 March 1987	Mertzon, US	daily rain	2.5 mm (0.10 in)	2.5 mm (0.10 in)	45 years	19 of 100 (Routine)
17 March 1987	Mertzon, US	daily rain	27.9 mm (1.1 in)	8.8 mm (0.35 in)	45 years	27 of 100 (Routine)
27 February 1987	Mertzon, US	daily rain	20.3 mm (0.8 in)	17.0 mm (0.7 in)	43 years	20 of 100 (Routine)
5 February 1987	Mertzon, US	monthly rain	83.8 mm (3.3 in)	36.0 mm (1.4 in)	4 years	53 of 100 (Notable)
17 January 1987	Mertzon, US	daily snowfall	0.3 cm (0.1 in)	0.3 cm (0.1 in)	45 years	17 of 100 (Routine)
22 December 1986	Mertzon, US	daily rain	33.0 mm (1.3 in)	33.0 mm (1.3 in)	44 years	48 of 100 (Notable)
18 December 1986	Mertzon, US	daily rain	22.9 mm (0.9 in)	7.7 mm (0.30 in)	33 years	20 of 100 (Routine)
14 December 1986	Mertzon, US	daily rain	12.7 mm (0.5 in)	3.3 mm (0.13 in)	1 year	7 of 100 (Routine)
11 December 1986	Mertzon, US	daily snowfall	0.3 cm (0.1 in)	0.3 cm (0.1 in)	44 years	17 of 100 (Routine)
10 December 1986	Mertzon, US	monthly snowfall (Tie)	11.4 cm (4.5 in)	tie	39 years	6 of 100 (Routine)
8 October 1986	Mertzon, US	daily rain	61.0 mm (2.4 in)	28.5 mm (1.1 in)	24 years	30 of 100 (Routine)
5 September 1986	Mertzon, US	daily rain	45.7 mm (1.8 in)	24.4 mm (1.0 in)	36 years	27 of 100 (Routine)
25 August 1986	Mertzon, US	daily rain	41.9 mm (1.6 in)	28.9 mm (1.1 in)	7 years	18 of 100 (Routine)
9 June 1986	Mertzon, US	daily rain	17.8 mm (0.7 in)	9.9 mm (0.39 in)	5 years	10 of 100 (Routine)
2 June 1986	Mertzon, US	daily rain	40.6 mm (1.6 in)	21.0 mm (0.8 in)	28 years	24 of 100 (Routine)

Extremes by Year

1941 to 1987

Yearly extremes at Mertzon: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	42.2 C (108.0 F)	1967	40.0 C (104.0 F)	25
Coldest night (TNn)	-15.6 C (3.9 F)	1972	-11.7 C (10.9 F)	25
Wettest day (Rx1day)	212.1 mm (8.4 in)	1971	53.8 mm (2.1 in)	47
Wettest five days (Rx5day)	358.2 mm (14.1 in)	1971	76.1 mm (3.0 in)	47
Longest dry spell (CDD)	98 days	1950	42 days	47

Hottest day (TXx)

The hottest day of the year at Mertzon, 1941 to 1987. The record is 42.2 C (108.0 F) in 1967, marked on the chart; the median year is 40.0 C (104.0 F).

Hottest day (TXx) at Mertzon by year
Year	Hottest day (TXx)
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	37.8 C (100.0 F)
1964	41.1 C (106.0 F)
1965	39.4 C (102.9 F)
1966	41.7 C (107.1 F)
1967	42.2 C (108.0 F)
1968	38.9 C (102.0 F)
1969	42.2 C (108.0 F)
1970	40.0 C (104.0 F)
1971	39.4 C (102.9 F)
1972	40.6 C (105.1 F)
1973	40.6 C (105.1 F)
1974	39.4 C (102.9 F)
1975	36.7 C (98.1 F)
1976	37.8 C (100.0 F)
1977	40.6 C (105.1 F)
1978	41.1 C (106.0 F)
1979	37.8 C (100.0 F)
1980	42.2 C (108.0 F)
1981	38.9 C (102.0 F)
1982	39.4 C (102.9 F)
1983	40.0 C (104.0 F)
1984	42.2 C (108.0 F)
1985	42.2 C (108.0 F)
1986	40.0 C (104.0 F)
1987	37.8 C (100.0 F)

Coldest night (TNn)

The coldest night of the year at Mertzon, 1941 to 1987. The record is -15.6 C (3.9 F) in 1972, marked on the chart; the median year is -11.7 C (10.9 F).

Coldest night (TNn) at Mertzon by year
Year	Coldest night (TNn)
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	-3.3 C (26.1 F)
1964	-6.7 C (19.9 F)
1965	-8.3 C (17.1 F)
1966	-12.8 C (9.0 F)
1967	-12.8 C (9.0 F)
1968	-11.1 C (12.0 F)
1969	-7.8 C (18.0 F)
1970	-12.2 C (10.0 F)
1971	-14.4 C (6.1 F)
1972	-15.6 C (3.9 F)
1973	-11.1 C (12.0 F)
1974	-10.6 C (12.9 F)
1975	-10.0 C (14.0 F)
1976	-10.6 C (12.9 F)
1977	-11.7 C (10.9 F)
1978	-11.7 C (10.9 F)
1979	-15.6 C (3.9 F)
1980	-13.9 C (7.0 F)
1981	-12.8 C (9.0 F)
1982	-15.6 C (3.9 F)
1983	-15.0 C (5.0 F)
1984	-5.0 C (23.0 F)
1985	-15.6 C (3.9 F)
1986	-5.6 C (21.9 F)
1987	-5.6 C (21.9 F)

Wettest day (Rx1day)

The wettest day of the year at Mertzon, 1941 to 1987. The record is 212.1 mm (8.4 in) in 1971, marked on the chart; the median year is 53.8 mm (2.1 in).

Wettest day (Rx1day) at Mertzon by year
Year	Wettest day (Rx1day)
1941	53.8 mm (2.1 in)
1942	121.9 mm (4.8 in)
1943	53.3 mm (2.1 in)
1944	73.9 mm (2.9 in)
1945	104.1 mm (4.1 in)
1946	53.8 mm (2.1 in)
1947	41.4 mm (1.6 in)
1948	40.1 mm (1.6 in)
1949	41.9 mm (1.6 in)
1950	54.4 mm (2.1 in)
1951	34.5 mm (1.4 in)
1952	36.1 mm (1.4 in)
1953	51.3 mm (2.0 in)
1954	39.4 mm (1.6 in)
1955	48.3 mm (1.9 in)
1956	35.6 mm (1.4 in)
1957	52.1 mm (2.1 in)
1958	83.8 mm (3.3 in)
1959	96.5 mm (3.8 in)
1960	28.4 mm (1.1 in)
1961	83.8 mm (3.3 in)
1962	43.4 mm (1.7 in)
1963	59.7 mm (2.4 in)
1964	36.8 mm (1.4 in)
1965	28.7 mm (1.1 in)
1966	53.8 mm (2.1 in)
1967	48.5 mm (1.9 in)
1968	71.6 mm (2.8 in)
1969	39.9 mm (1.6 in)
1970	34.0 mm (1.3 in)
1971	212.1 mm (8.4 in)
1972	72.4 mm (2.9 in)
1973	86.4 mm (3.4 in)
1974	63.5 mm (2.5 in)
1975	99.1 mm (3.9 in)
1976	48.3 mm (1.9 in)
1977	53.6 mm (2.1 in)
1978	59.2 mm (2.3 in)
1979	40.1 mm (1.6 in)
1980	73.7 mm (2.9 in)
1981	68.8 mm (2.7 in)
1982	66.0 mm (2.6 in)
1983	83.1 mm (3.3 in)
1984	66.0 mm (2.6 in)
1985	58.4 mm (2.3 in)
1986	61.0 mm (2.4 in)
1987	83.8 mm (3.3 in)

Wettest five days (Rx5day)

The wettest five days of the year at Mertzon, 1941 to 1987. The record is 358.2 mm (14.1 in) in 1971, marked on the chart; the median year is 76.1 mm (3.0 in).

Wettest five days (Rx5day) at Mertzon by year
Year	Wettest five days (Rx5day)
1941	81.3 mm (3.2 in)
1942	128.3 mm (5.1 in)
1943	98.5 mm (3.9 in)
1944	73.9 mm (2.9 in)
1945	131.1 mm (5.2 in)
1946	61.4 mm (2.4 in)
1947	41.4 mm (1.6 in)
1948	57.4 mm (2.3 in)
1949	76.2 mm (3.0 in)
1950	81.6 mm (3.2 in)
1951	38.1 mm (1.5 in)
1952	38.9 mm (1.5 in)
1953	87.4 mm (3.4 in)
1954	47.2 mm (1.9 in)
1955	69.3 mm (2.7 in)
1956	38.9 mm (1.5 in)
1957	124.5 mm (4.9 in)
1958	85.8 mm (3.4 in)
1959	180.1 mm (7.1 in)
1960	38.1 mm (1.5 in)
1961	156.6 mm (6.2 in)
1962	43.4 mm (1.7 in)
1963	61.0 mm (2.4 in)
1964	70.1 mm (2.8 in)
1965	48.0 mm (1.9 in)
1966	75.7 mm (3.0 in)
1967	56.9 mm (2.2 in)
1968	71.6 mm (2.8 in)
1969	60.4 mm (2.4 in)
1970	34.0 mm (1.3 in)
1971	358.2 mm (14.1 in)
1972	72.4 mm (2.9 in)
1973	113.8 mm (4.5 in)
1974	140.9 mm (5.5 in)
1975	131.6 mm (5.2 in)
1976	106.9 mm (4.2 in)
1977	102.4 mm (4.0 in)
1978	59.5 mm (2.3 in)
1979	61.2 mm (2.4 in)
1980	107.2 mm (4.2 in)
1981	106.4 mm (4.2 in)
1982	66.0 mm (2.6 in)
1983	83.1 mm (3.3 in)
1984	76.1 mm (3.0 in)
1985	149.9 mm (5.9 in)
1986	97.8 mm (3.9 in)
1987	96.5 mm (3.8 in)

Longest dry spell (CDD)

The longest dry spell of the year at Mertzon, 1941 to 1987. The record is 98 days in 1950, marked on the chart; the median year is 42 days.

Longest dry spell (CDD) at Mertzon by year
Year	Longest dry spell (CDD)
1941	28 days
1942	43 days
1943	76 days
1944	38 days
1945	38 days
1946	42 days
1947	39 days
1948	34 days
1949	39 days
1950	98 days
1951	33 days
1952	42 days
1953	57 days
1954	44 days
1955	50 days
1956	41 days
1957	33 days
1958	33 days
1959	31 days
1960	45 days
1961	28 days
1962	45 days
1963	31 days
1964	41 days
1965	43 days
1966	75 days
1967	36 days
1968	30 days
1969	44 days
1970	59 days
1971	67 days
1972	59 days
1973	48 days
1974	42 days
1975	37 days
1976	36 days
1977	45 days
1978	50 days
1979	50 days
1980	55 days
1981	70 days
1982	36 days
1983	47 days
1984	38 days
1985	38 days
1986	52 days
1987	25 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

36 years, 1941 to 1986

A day with at least 54.7 mm (2.2 in) of rain is expected about once in 2 years. A day with at least 133.4 mm (5.3 in) of rain is expected about once in 100 years.

Rainfall return levels at Mertzon: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	54.7 mm (2.2 in)
5 years	73.5 mm (2.9 in)
10 years	86.8 mm (3.4 in)
25 years	104.6 mm (4.1 in)
50 years	118.7 mm (4.7 in)	Longer than the 36 years of record
100 years	133.4 mm (5.3 in)	Longer than the 36 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, 36 years of values from 1941 to 1986.

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: 121.9 mm (4.8 in) in 1942; 104.1 mm (4.1 in) in 1945; 96.5 mm (3.8 in) in 1959.

Download the Data

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