Atotonilco Weather Records (MXN00015010)

Record envelope, standing records and threshold days for Atotonilco (MXN00015010), Mexico, with 52 years of record.

Key Facts for Atotonilco

Atotonilco (MXN00015010) is a weather station in Mexico at 19.45 latitude and -99.77 longitude, 2,557 m (8,389 ft) above sea level.
The station reports from 1961 to 2012, 52 years of record.
1,464 records set at Atotonilco still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
Atotonilco tied a daily record low minimum temperature of -5.0 C (23.0 F) on 7 December 2012.

About the Station

Location: Mexico, 19.45 latitude, -99.77 longitude.
Elevation: 2,557 m (8,389 ft).
Period of record: 1961 to 2012, 52 years.
Eligible elements: tmax, tmin, 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 Atotonilco. 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 Atotonilco, 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)	-10.6 C (12.9 F)	n/a	n/a
Feb	26.7 C (80.1 F)	-9.4 C (15.1 F)	n/a	n/a
Mar	30.0 C (86.0 F)	-8.3 C (17.1 F)	n/a	n/a
Apr	31.7 C (89.1 F)	-5.0 C (23.0 F)	n/a	n/a
May	30.6 C (87.1 F)	-3.3 C (26.1 F)	n/a	n/a
Jun	28.9 C (84.0 F)	0.0 C (32.0 F)	n/a	n/a
Jul	28.3 C (82.9 F)	2.8 C (37.0 F)	n/a	n/a
Aug	25.6 C (78.1 F)	1.7 C (35.1 F)	n/a	n/a
Sep	27.2 C (81.0 F)	-2.2 C (28.0 F)	n/a	n/a
Oct	27.2 C (81.0 F)	-4.4 C (24.1 F)	n/a	n/a
Nov	26.7 C (80.1 F)	-8.3 C (17.1 F)	n/a	n/a
Dec	25.0 C (77.0 F)	-12.2 C (10.0 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Atotonilco still stand. 1965 holds the most, with 76.

Standing records at Atotonilco by the year they were set
Year set	Standing records
1961	25
1962	48
1963	38
1964	33
1965	76
1966	72
1967	52
1968	23
1969	63
1970	28
1971	19
1972	39
1973	42
1974	27
1975	21
1976	37
1977	19
1978	23
1979	31
1980	20
1981	18
1982	26
1983	42
1984	13
1985	13
1986	21
1987	22
1988	22
1989	24
1990	22
1991	9
1992	40
1995	26
1996	17
1997	30
1998	57
1999	37
2000	18
2001	23
2002	21
2003	26
2004	23
2005	24
2006	35
2007	25
2008	19
2009	16
2010	40
2012	19

All-Time Record Progression

4 new records

4 all-time records were set at Atotonilco between 26 August 1999 and 27 December 2006. Each dot is a new record.

When Atotonilco set new all-time records
Date	Kind	Detail
1999-08-26	Record high minimum temperature	Record high minimum temperature 13.9 C (57.0 F)
2006-05-26	Record daily precipitation	Record daily precipitation 74.9 mm (2.9 in)
2006-12-26	Record low minimum temperature	Record low minimum temperature -11.1 C (12.0 F)
2006-12-27	Record low minimum temperature	Record low minimum temperature -12.2 C (10.0 F)

Wettest Day of Each Month

May: 74.9 mm (2.9 in)

The wettest day on record for each calendar month at Atotonilco. The most was 74.9 mm (2.9 in) on 26 May 2006.

Record daily precipitation for each month at Atotonilco
Month	Record daily precipitation (mm)	Date
Jan	53.8 mm (2.1 in)	30 January 1992
Feb	49.8 mm (2.0 in)	4 February 2010
Mar	46.0 mm (1.8 in)	17 March 1976
Apr	41.9 mm (1.6 in)	13 April 1962
May	74.9 mm (2.9 in)	26 May 2006
Jun	65.3 mm (2.6 in)	15 June 1981
Jul	69.9 mm (2.8 in)	8 July 2010
Aug	71.6 mm (2.8 in)	15 August 1989
Sep	68.8 mm (2.7 in)	4 September 2004
Oct	44.2 mm (1.7 in)	14 October 1966
Nov	39.4 mm (1.6 in)	2 November 1972
Dec	27.2 mm (1.1 in)	3 December 1981

Period of Record Coverage

1961 to 2012

50 years of record at Atotonilco, 1961 to 2012. 8 years have data for under 90 percent of days and are left out of rankings: 1961, 1994, 1995, 1998, 1999, 2001, 2002, 2012.

Days with data per year at Atotonilco
Year	Days with data	Share of year	Complete
1961	122	33%	No
1962	365	100%	Yes
1963	365	100%	Yes
1964	337	92%	Yes
1965	365	100%	Yes
1966	365	100%	Yes
1967	364	100%	Yes
1968	363	99%	Yes
1969	364	100%	Yes
1970	364	100%	Yes
1971	365	100%	Yes
1972	366	100%	Yes
1973	365	100%	Yes
1974	365	100%	Yes
1975	365	100%	Yes
1976	361	99%	Yes
1977	365	100%	Yes
1978	361	99%	Yes
1979	365	100%	Yes
1980	366	100%	Yes
1981	365	100%	Yes
1982	365	100%	Yes
1983	365	100%	Yes
1984	366	100%	Yes
1985	332	91%	Yes
1986	361	99%	Yes
1987	337	92%	Yes
1988	366	100%	Yes
1989	364	100%	Yes
1990	364	100%	Yes
1991	350	96%	Yes
1992	366	100%	Yes
1994	31	8%	No
1995	275	75%	No
1996	357	98%	Yes
1997	349	96%	Yes
1998	284	78%	No
1999	322	88%	No
2000	363	99%	Yes
2001	319	87%	No
2002	180	49%	No
2003	363	99%	Yes
2004	359	98%	Yes
2005	356	98%	Yes
2006	358	98%	Yes
2007	357	98%	Yes
2008	351	96%	Yes
2009	357	98%	Yes
2010	345	95%	Yes
2012	329	90%	No

Latest Records

Latest records at Atotonilco
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
7 December 2012	Atotonilco, MX	daily low min (Tie)	-5.0 C (23.0 F)	tie	4 years	1 of 100 (Routine)
21 November 2012	Atotonilco, MX	daily low min (Tie)	-5.0 C (23.0 F)	tie	10 years	2 of 100 (Routine)
6 November 2012	Atotonilco, MX	daily low max (Tie)	15.6 C (60.1 F)	tie	51 years	5 of 100 (Routine)
8 October 2012	Atotonilco, MX	daily low min	0.0 C (32.0 F)	1.7 C (3.1 F)	33 years	19 of 100 (Routine)
7 October 2012	Atotonilco, MX	daily low min	-1.1 C (30.0 F)	0.5 C (0.9 F)	33 years	15 of 100 (Routine)
6 October 2012	Atotonilco, MX	daily low min	-2.2 C (28.0 F)	3.9 C (7.0 F)	2 years	17 of 100 (Routine)
5 October 2012	Atotonilco, MX	daily low min	-1.1 C (30.0 F)	1.1 C (2.0 F)	2 years	8 of 100 (Routine)
4 October 2012	Atotonilco, MX	daily low min (Tie)	0.0 C (32.0 F)	tie	33 years	3 of 100 (Routine)
30 September 2012	Atotonilco, MX	daily rain	33.8 mm (1.3 in)	18.8 mm (0.7 in)	14 years	31 of 100 (Routine)
20 September 2012	Atotonilco, MX	daily low min (Tie)	3.9 C (39.0 F)	tie	37 years	4 of 100 (Routine)
19 September 2012	Atotonilco, MX	daily low min	3.9 C (39.0 F)	1.1 C (2.0 F)	45 years	23 of 100 (Routine)
16 September 2012	Atotonilco, MX	daily rain	17.3 mm (0.7 in)	0.3 mm (0.01 in)	36 years	15 of 100 (Routine)
15 September 2012	Atotonilco, MX	daily low min	5.0 C (41.0 F)	0.6 C (1.1 F)	6 years	8 of 100 (Routine)
4 September 2012	Atotonilco, MX	daily low min (Tie)	5.0 C (41.0 F)	tie	27 years	3 of 100 (Routine)
27 August 2012	Atotonilco, MX	daily rain	30.0 mm (1.2 in)	3.3 mm (0.13 in)	31 years	18 of 100 (Routine)
19 August 2012	Atotonilco, MX	daily low max (Tie)	17.8 C (64.0 F)	tie	36 years	3 of 100 (Routine)
14 August 2012	Atotonilco, MX	daily rain	26.7 mm (1.1 in)	1.3 mm (0.05 in)	31 years	15 of 100 (Routine)
12 August 2012	Atotonilco, MX	daily low max	17.8 C (64.0 F)	0.5 C (0.9 F)	33 years	17 of 100 (Routine)
11 August 2012	Atotonilco, MX	daily low max	15.6 C (60.1 F)	2.7 C (4.9 F)	39 years	34 of 100 (Routine)
14 July 2012	Atotonilco, MX	daily rain	27.9 mm (1.1 in)	8.8 mm (0.35 in)	35 years	26 of 100 (Routine)

Climate Trend

38 complete years, 1962 to 2010

One stripe for each of 38 complete years at Atotonilco, 1962 to 2010. Blue stripes are years cooler than the station's own mean of 12.7 C (54.9 F); red stripes are warmer. The coolest year was 2008, at 11.5 C (52.7 F), and the warmest was 1966, at 13.7 C (56.6 F). The strongest colour marks a difference of 1.3 C (2.3 F).

Annual mean temperature at Atotonilco as warming stripes, 1962 to 2010
Year	Annual mean temperature	Difference from the station mean
1962	13.3 C	+0.62 C
1963	13.3 C	+0.54 C
1965	13.4 C	+0.71 C
1966	13.7 C	+0.94 C
1967	13.5 C	+0.74 C
1968	13.2 C	+0.50 C
1969	13.6 C	+0.90 C
1970	13.3 C	+0.54 C
1971	13.2 C	+0.47 C
1972	13.5 C	+0.80 C
1973	13.4 C	+0.64 C
1974	13.1 C	+0.39 C
1975	12.5 C	-0.17 C
1976	12.7 C	-0.05 C
1977	12.8 C	+0.08 C
1978	12.9 C	+0.23 C
1979	12.8 C	+0.09 C
1980	13.0 C	+0.26 C
1981	12.8 C	+0.11 C
1982	12.8 C	+0.06 C
1983	12.3 C	-0.45 C
1984	12.6 C	-0.12 C
1986	12.4 C	-0.31 C
1988	12.6 C	-0.08 C
1989	12.5 C	-0.26 C
1990	12.8 C	+0.13 C
1992	12.3 C	-0.38 C
1996	12.9 C	+0.14 C
1997	13.0 C	+0.25 C
2000	12.7 C	+0.03 C
2003	12.1 C	-0.58 C
2004	12.0 C	-0.75 C
2005	11.9 C	-0.84 C
2006	11.5 C	-1.18 C
2007	11.6 C	-1.08 C
2008	11.5 C	-1.23 C
2009	12.1 C	-0.63 C
2010	11.5 C	-1.19 C

The annual mean temperature here has fallen by 0.4 C (0.3 to 0.4) per decade over 1962 to 2010. In Fahrenheit: 0.6 F (0.5 to 0.8) per decade. The slope is a straight line fitted to 38 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at Atotonilco
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	-0.4 C (-0.4 to -0.3) per decade	-0.6 F (-0.8 to -0.5) per decade	1962 to 2010	38	Fall
Mean daily maximum	-0.2 C (-0.3 to -0.1) per decade	-0.4 F (-0.6 to -0.2) per decade	1962 to 2010	38	Fall
Mean daily minimum	-0.5 C (-0.7 to -0.4) per decade	-0.9 F (-1.2 to -0.7) per decade	1962 to 2010	38	Fall

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

1961 to 2012

Yearly extremes at Atotonilco: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	31.7 C (89.1 F)	1966	27.8 C (82.0 F)	50
Coldest night (TNn)	-12.2 C (10.0 F)	2006	-6.7 C (19.9 F)	50
Wettest day (Rx1day)	74.9 mm (2.9 in)	2006	43.3 mm (1.7 in)	50
Wettest five days (Rx5day)	136.2 mm (5.4 in)	2004	78.8 mm (3.1 in)	50
Longest dry spell (CDD)	127 days	1998	46 days	50

Hottest day (TXx)

The hottest day of the year at Atotonilco, 1961 to 2012. The record is 31.7 C (89.1 F) in 1966, marked on the chart; the median year is 27.8 C (82.0 F).

Hottest day (TXx) at Atotonilco by year
Year	Hottest day (TXx)
1961	25.6 C (78.1 F)
1962	30.0 C (86.0 F)
1963	30.0 C (86.0 F)
1964	30.0 C (86.0 F)
1965	28.9 C (84.0 F)
1966	31.7 C (89.1 F)
1967	30.0 C (86.0 F)
1968	27.8 C (82.0 F)
1969	28.9 C (84.0 F)
1970	28.9 C (84.0 F)
1971	28.9 C (84.0 F)
1972	27.8 C (82.0 F)
1973	29.4 C (84.9 F)
1974	28.3 C (82.9 F)
1975	27.2 C (81.0 F)
1976	25.6 C (78.1 F)
1977	27.8 C (82.0 F)
1978	29.4 C (84.9 F)
1979	26.7 C (80.1 F)
1980	28.3 C (82.9 F)
1981	26.7 C (80.1 F)
1982	26.7 C (80.1 F)
1983	30.0 C (86.0 F)
1984	27.8 C (82.0 F)
1985	27.2 C (81.0 F)
1986	26.7 C (80.1 F)
1987	28.3 C (82.9 F)
1988	28.3 C (82.9 F)
1989	28.3 C (82.9 F)
1990	26.7 C (80.1 F)
1991	28.3 C (82.9 F)
1992	26.1 C (79.0 F)
1994	21.7 C (71.1 F)
1995	27.8 C (82.0 F)
1996	27.8 C (82.0 F)
1997	28.3 C (82.9 F)
1998	30.6 C (87.1 F)
1999	26.7 C (80.1 F)
2000	27.2 C (81.0 F)
2001	27.2 C (81.0 F)
2002	27.8 C (82.0 F)
2003	28.9 C (84.0 F)
2004	26.7 C (80.1 F)
2005	28.9 C (84.0 F)
2006	28.9 C (84.0 F)
2007	27.8 C (82.0 F)
2008	27.8 C (82.0 F)
2009	27.8 C (82.0 F)
2010	28.9 C (84.0 F)
2012	27.8 C (82.0 F)

Coldest night (TNn)

The coldest night of the year at Atotonilco, 1961 to 2012. The record is -12.2 C (10.0 F) in 2006, marked on the chart; the median year is -6.7 C (19.9 F).

Coldest night (TNn) at Atotonilco by year
Year	Coldest night (TNn)
1961	-6.7 C (19.9 F)
1962	-6.7 C (19.9 F)
1963	-8.3 C (17.1 F)
1964	-3.9 C (25.0 F)
1965	-8.3 C (17.1 F)
1966	-6.7 C (19.9 F)
1967	-6.7 C (19.9 F)
1968	-6.7 C (19.9 F)
1969	-6.7 C (19.9 F)
1970	-5.6 C (21.9 F)
1971	-5.6 C (21.9 F)
1972	-5.6 C (21.9 F)
1973	-6.1 C (21.0 F)
1974	-6.1 C (21.0 F)
1975	-8.3 C (17.1 F)
1976	-8.9 C (16.0 F)
1977	-4.4 C (24.1 F)
1978	-4.4 C (24.1 F)
1979	-6.1 C (21.0 F)
1980	-7.2 C (19.0 F)
1981	-6.1 C (21.0 F)
1982	-8.3 C (17.1 F)
1983	-8.9 C (16.0 F)
1984	-4.4 C (24.1 F)
1985	-4.4 C (24.1 F)
1986	-9.4 C (15.1 F)
1987	-8.9 C (16.0 F)
1988	-10.6 C (12.9 F)
1989	-7.2 C (19.0 F)
1990	-7.2 C (19.0 F)
1991	-5.0 C (23.0 F)
1992	-6.1 C (21.0 F)
1994	-3.3 C (26.1 F)
1995	-4.4 C (24.1 F)
1996	-6.1 C (21.0 F)
1997	-9.4 C (15.1 F)
1998	-9.4 C (15.1 F)
1999	-10.0 C (14.0 F)
2000	-6.1 C (21.0 F)
2001	-4.4 C (24.1 F)
2002	-8.3 C (17.1 F)
2003	-7.2 C (19.0 F)
2004	-9.4 C (15.1 F)
2005	-7.2 C (19.0 F)
2006	-12.2 C (10.0 F)
2007	-7.2 C (19.0 F)
2008	-7.2 C (19.0 F)
2009	-7.2 C (19.0 F)
2010	-12.2 C (10.0 F)
2012	-5.0 C (23.0 F)

Wettest day (Rx1day)

The wettest day of the year at Atotonilco, 1961 to 2012. The record is 74.9 mm (2.9 in) in 2006, marked on the chart; the median year is 43.3 mm (1.7 in).

Wettest day (Rx1day) at Atotonilco by year
Year	Wettest day (Rx1day)
1961	31.5 mm (1.2 in)
1962	41.9 mm (1.6 in)
1963	46.2 mm (1.8 in)
1964	31.0 mm (1.2 in)
1965	50.8 mm (2.0 in)
1966	50.3 mm (2.0 in)
1967	47.5 mm (1.9 in)
1968	32.3 mm (1.3 in)
1969	38.9 mm (1.5 in)
1970	32.5 mm (1.3 in)
1971	37.8 mm (1.5 in)
1972	39.4 mm (1.6 in)
1973	50.5 mm (2.0 in)
1974	48.8 mm (1.9 in)
1975	48.3 mm (1.9 in)
1976	46.0 mm (1.8 in)
1977	28.2 mm (1.1 in)
1978	33.8 mm (1.3 in)
1979	33.0 mm (1.3 in)
1980	44.2 mm (1.7 in)
1981	65.3 mm (2.6 in)
1982	31.0 mm (1.2 in)
1983	37.8 mm (1.5 in)
1984	24.6 mm (1.0 in)
1985	43.2 mm (1.7 in)
1986	29.7 mm (1.2 in)
1987	53.8 mm (2.1 in)
1988	45.0 mm (1.8 in)
1989	71.6 mm (2.8 in)
1990	46.0 mm (1.8 in)
1991	32.0 mm (1.3 in)
1992	53.8 mm (2.1 in)
1994	0.3 mm (0.01 in)
1995	59.9 mm (2.4 in)
1996	39.9 mm (1.6 in)
1997	42.9 mm (1.7 in)
1998	43.4 mm (1.7 in)
1999	39.9 mm (1.6 in)
2000	46.0 mm (1.8 in)
2001	43.9 mm (1.7 in)
2002	37.8 mm (1.5 in)
2003	40.9 mm (1.6 in)
2004	68.8 mm (2.7 in)
2005	43.7 mm (1.7 in)
2006	74.9 mm (2.9 in)
2007	41.9 mm (1.6 in)
2008	46.0 mm (1.8 in)
2009	47.8 mm (1.9 in)
2010	69.9 mm (2.8 in)
2012	33.8 mm (1.3 in)

Wettest five days (Rx5day)

The wettest five days of the year at Atotonilco, 1961 to 2012. The record is 136.2 mm (5.4 in) in 2004, marked on the chart; the median year is 78.8 mm (3.1 in).

Wettest five days (Rx5day) at Atotonilco by year
Year	Wettest five days (Rx5day)
1961	58.9 mm (2.3 in)
1962	75.1 mm (3.0 in)
1963	101.9 mm (4.0 in)
1964	78.5 mm (3.1 in)
1965	94.0 mm (3.7 in)
1966	87.6 mm (3.4 in)
1967	69.0 mm (2.7 in)
1968	57.5 mm (2.3 in)
1969	98.6 mm (3.9 in)
1970	86.8 mm (3.4 in)
1971	75.2 mm (3.0 in)
1972	62.2 mm (2.4 in)
1973	79.0 mm (3.1 in)
1974	89.8 mm (3.5 in)
1975	59.3 mm (2.3 in)
1976	99.1 mm (3.9 in)
1977	78.7 mm (3.1 in)
1978	74.9 mm (2.9 in)
1979	54.3 mm (2.1 in)
1980	103.2 mm (4.1 in)
1981	98.6 mm (3.9 in)
1982	74.7 mm (2.9 in)
1983	85.0 mm (3.3 in)
1984	72.7 mm (2.9 in)
1985	78.5 mm (3.1 in)
1986	48.1 mm (1.9 in)
1987	83.5 mm (3.3 in)
1988	73.7 mm (2.9 in)
1989	85.6 mm (3.4 in)
1990	69.1 mm (2.7 in)
1991	77.0 mm (3.0 in)
1992	122.4 mm (4.8 in)
1994	0.3 mm (0.01 in)
1995	86.8 mm (3.4 in)
1996	73.4 mm (2.9 in)
1997	54.6 mm (2.1 in)
1998	115.1 mm (4.5 in)
1999	60.3 mm (2.4 in)
2000	111.8 mm (4.4 in)
2001	78.8 mm (3.1 in)
2002	71.4 mm (2.8 in)
2003	105.7 mm (4.2 in)
2004	136.2 mm (5.4 in)
2005	76.0 mm (3.0 in)
2006	98.9 mm (3.9 in)
2007	96.5 mm (3.8 in)
2008	102.9 mm (4.1 in)
2009	124.8 mm (4.9 in)
2010	110.6 mm (4.4 in)
2012	66.9 mm (2.6 in)

Longest dry spell (CDD)

The longest dry spell of the year at Atotonilco, 1961 to 2012. The record is 127 days in 1998, marked on the chart; the median year is 46 days.

Longest dry spell (CDD) at Atotonilco by year
Year	Longest dry spell (CDD)
1961	48 days
1962	65 days
1963	65 days
1964	29 days
1965	34 days
1966	49 days
1967	27 days
1968	26 days
1969	90 days
1970	46 days
1971	75 days
1972	36 days
1973	57 days
1974	38 days
1975	46 days
1976	41 days
1977	32 days
1978	37 days
1979	41 days
1980	55 days
1981	38 days
1982	38 days
1983	68 days
1984	54 days
1985	44 days
1986	98 days
1987	41 days
1988	61 days
1989	52 days
1990	30 days
1991	42 days
1992	37 days
1994	31 days
1995	39 days
1996	68 days
1997	61 days
1998	127 days
1999	34 days
2000	56 days
2001	32 days
2002	46 days
2003	75 days
2004	31 days
2005	50 days
2006	59 days
2007	36 days
2008	77 days
2009	46 days
2010	80 days
2012	55 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

38 years with a frost

Across 38 years with a frost, the median last spring frost at Atotonilco falls on 14 April and the median first autumn frost on 2 November, which leaves a median of 205 days between them.

Fitted over all years, the growing season changes by -11.0 days per decade at this station.

Frost dates and growing season at Atotonilco
Measure	Median, all years	Earliest period	Recent period (1971 to 2010)	Recent against earliest	Fitted trend
Last spring frost	14 April	n/a	16 April	n/a	+6.9 days per decade
First autumn frost	2 November	n/a	3 November	n/a	-4.1 days per decade
Growing days	205 days	n/a	202 days	n/a	-11.0 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

44 years, 1961 to 2012

A day with at least 42.3 mm (1.7 in) of rain is expected about once in 2 years. A day with at least 81.4 mm (3.2 in) of rain is expected about once in 100 years.

Rainfall return levels at Atotonilco: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	42.3 mm (1.7 in)
5 years	52.9 mm (2.1 in)
10 years	59.9 mm (2.4 in)
25 years	68.6 mm (2.7 in)
50 years	75.0 mm (3.0 in)	Longer than the 44 years of record
100 years	81.4 mm (3.2 in)	Longer than the 44 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, 44 years of values from 1961 to 2012.

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: 74.9 mm (2.9 in) in 2006; 71.6 mm (2.8 in) in 1989; 69.9 mm (2.8 in) in 2010.

Download the Data

Data for Atotonilco standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Atotonilco 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 2026-10-17 (17 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).