San Juan Weather Records (MXN00019056)

Record envelope, standing records and threshold days for San Juan (MXN00019056), Mexico, with 65 years of record.

Key Facts for San Juan

San Juan (MXN00019056) is a weather station in Mexico at 25.53 latitude and -99.83 longitude, 260 m (853 ft) above sea level.
The station reports from 1947 to 2011, 65 years of record.
1,464 records set at San Juan still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
San Juan tied a daily record high maximum temperature of 42.8 C (109.0 F) on 22 June 2011.

About the Station

Location: Mexico, 25.53 latitude, -99.83 longitude.
Elevation: 260 m (853 ft).
Period of record: 1947 to 2011, 65 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 San Juan. 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 San Juan, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	38.9 C (102.0 F)	-6.1 C (21.0 F)	n/a	n/a
Feb	40.0 C (104.0 F)	-5.6 C (21.9 F)	n/a	n/a
Mar	43.9 C (111.0 F)	-2.8 C (27.0 F)	n/a	n/a
Apr	45.0 C (113.0 F)	0.6 C (33.1 F)	n/a	n/a
May	45.0 C (113.0 F)	6.7 C (44.1 F)	n/a	n/a
Jun	46.1 C (115.0 F)	11.7 C (53.1 F)	n/a	n/a
Jul	45.6 C (114.1 F)	13.9 C (57.0 F)	n/a	n/a
Aug	45.0 C (113.0 F)	11.7 C (53.1 F)	n/a	n/a
Sep	43.9 C (111.0 F)	9.4 C (48.9 F)	n/a	n/a
Oct	40.0 C (104.0 F)	1.1 C (34.0 F)	n/a	n/a
Nov	40.0 C (104.0 F)	0.0 C (32.0 F)	n/a	n/a
Dec	40.0 C (104.0 F)	-8.3 C (17.1 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at San Juan still stand. 1971 holds the most, with 93.

Standing records at San Juan by the year they were set
Year set	Standing records
1950	12
1951	37
1952	20
1953	58
1954	17
1955	34
1956	31
1957	54
1958	43
1959	69
1960	54
1961	61
1962	13
1963	20
1964	3
1965	26
1966	17
1967	16
1968	18
1969	67
1970	15
1971	93
1972	43
1973	29
1974	19
1975	25
1976	30
1977	8
1978	23
1979	21
1980	12
1981	21
1982	18
1983	28
1984	8
1985	20
1986	12
1987	23
1988	9
1989	37
1990	18
1991	30
1992	27
1993	15
1994	12
1995	14
1996	18
1997	21
1998	35
1999	4
2000	11
2001	16
2002	11
2003	2
2004	6
2005	12
2006	13
2008	6
2009	7
2010	9
2011	13

All-Time Record Progression

7 new records

7 all-time records were set at San Juan between 1 June 1979 and 15 June 1998. Each dot is a new record.

When San Juan set new all-time records
Date	Kind	Detail
1979-06-01	Record daily precipitation	Record daily precipitation 143.3 mm (5.6 in)
1983-09-11	Record daily precipitation	Record daily precipitation 143.8 mm (5.7 in)
1983-12-25	Record low minimum temperature	Record low minimum temperature -8.3 C (17.1 F)
1988-09-16	Record daily precipitation	Record daily precipitation 170.2 mm (6.7 in)
1997-01-13	Record low maximum temperature	Record low maximum temperature -1.1 C (30.0 F)
1998-06-14	Record high maximum temperature	Record high maximum temperature 45.6 C (114.1 F)
1998-06-15	Record high maximum temperature	Record high maximum temperature 46.1 C (115.0 F)

Wettest Day of Each Month

Sep: 170.2 mm (6.7 in)

The wettest day on record for each calendar month at San Juan. The most was 170.2 mm (6.7 in) on 16 September 1988.

Record daily precipitation for each month at San Juan
Month	Record daily precipitation (mm)	Date
Jan	99.8 mm (3.9 in)	4 January 1958
Feb	118.9 mm (4.7 in)	19 February 1970
Mar	60.2 mm (2.4 in)	18 March 1997
Apr	129.8 mm (5.1 in)	8 April 1954
May	100.1 mm (3.9 in)	2 May 1981
Jun	160.8 mm (6.3 in)	30 June 2010
Jul	134.9 mm (5.3 in)	20 July 2005
Aug	97.8 mm (3.9 in)	11 August 1995
Sep	170.2 mm (6.7 in)	16 September 1988
Oct	129.8 mm (5.1 in)	6 October 2000
Nov	95.0 mm (3.7 in)	5 November 1961
Dec	54.9 mm (2.2 in)	8 December 1982

Period of Record Coverage

1950 to 2011

61 years of record at San Juan, 1950 to 2011. 8 years have data for under 90 percent of days and are left out of rankings: 1950, 1960, 1961, 1984, 2000, 2003, 2009, 2011.

Days with data per year at San Juan
Year	Days with data	Share of year	Complete
1950	70	19%	No
1951	362	99%	Yes
1952	361	99%	Yes
1953	362	99%	Yes
1954	364	100%	Yes
1955	362	99%	Yes
1956	365	100%	Yes
1957	364	100%	Yes
1958	361	99%	Yes
1959	361	99%	Yes
1960	91	25%	No
1961	162	44%	No
1962	346	95%	Yes
1963	333	91%	Yes
1964	337	92%	Yes
1965	365	100%	Yes
1966	357	98%	Yes
1967	333	91%	Yes
1968	366	100%	Yes
1969	349	96%	Yes
1970	365	100%	Yes
1971	361	99%	Yes
1972	350	96%	Yes
1973	363	99%	Yes
1974	333	91%	Yes
1975	365	100%	Yes
1976	366	100%	Yes
1977	361	99%	Yes
1978	331	91%	Yes
1979	362	99%	Yes
1980	359	98%	Yes
1981	362	99%	Yes
1982	363	99%	Yes
1983	361	99%	Yes
1984	149	41%	No
1985	357	98%	Yes
1986	358	98%	Yes
1987	358	98%	Yes
1988	361	99%	Yes
1989	344	94%	Yes
1990	356	98%	Yes
1991	356	98%	Yes
1992	362	99%	Yes
1993	363	99%	Yes
1994	336	92%	Yes
1995	332	91%	Yes
1996	358	98%	Yes
1997	355	97%	Yes
1998	342	94%	Yes
1999	364	100%	Yes
2000	301	82%	No
2001	364	100%	Yes
2002	365	100%	Yes
2003	242	66%	No
2004	363	99%	Yes
2005	362	99%	Yes
2006	333	91%	Yes
2008	365	100%	Yes
2009	272	75%	No
2010	362	99%	Yes
2011	177	48%	No

Latest Records

Latest records at San Juan
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
22 June 2011	San Juan, MX	daily high max (Tie)	42.8 C (109.0 F)	tie	52 years	5 of 100 (Routine)
17 June 2011	San Juan, MX	daily high max (Tie)	42.8 C (109.0 F)	tie	57 years	5 of 100 (Routine)
26 May 2011	San Juan, MX	daily high min	25.0 C (77.0 F)	1.1 C (2.0 F)	57 years	26 of 100 (Routine)
25 May 2011	San Juan, MX	daily high min	25.0 C (77.0 F)	0.6 C (1.1 F)	21 years	13 of 100 (Routine)
24 May 2011	San Juan, MX	daily high min	25.6 C (78.1 F)	0.6 C (1.1 F)	56 years	23 of 100 (Routine)
23 May 2011	San Juan, MX	daily high min	25.0 C (77.0 F)	0.6 C (1.1 F)	20 years	13 of 100 (Routine)
19 May 2011	San Juan, MX	daily high max (Tie)	40.0 C (104.0 F)	tie	53 years	5 of 100 (Routine)
18 May 2011	San Juan, MX	daily high max (Tie)	40.0 C (104.0 F)	tie	53 years	5 of 100 (Routine)
13 May 2011	San Juan, MX	daily high min (Tie)	25.0 C (77.0 F)	tie	20 years	3 of 100 (Routine)
12 May 2011	San Juan, MX	daily high min (Tie)	25.0 C (77.0 F)	tie	20 years	3 of 100 (Routine)
26 April 2011	San Juan, MX	monthly high max (Tie)	45.0 C (113.0 F)	tie	48 years	7 of 100 (Routine)
25 April 2011	San Juan, MX	daily high max	43.9 C (111.0 F)	2.2 C (4.0 F)	14 years	14 of 100 (Routine)
22 April 2011	San Juan, MX	daily high min	23.3 C (73.9 F)	0.5 C (0.9 F)	40 years	19 of 100 (Routine)
11 April 2011	San Juan, MX	daily high min	22.2 C (72.0 F)	0.5 C (0.9 F)	40 years	19 of 100 (Routine)
8 March 2011	San Juan, MX	daily high max (Tie)	37.8 C (100.0 F)	tie	50 years	5 of 100 (Routine)
25 February 2011	San Juan, MX	daily high min	16.7 C (62.1 F)	0.6 C (1.1 F)	17 years	12 of 100 (Routine)
13 February 2011	San Juan, MX	daily low min (Tie)	-1.1 C (30.0 F)	tie	48 years	5 of 100 (Routine)
5 February 2011	San Juan, MX	daily low min (Tie)	-3.3 C (26.1 F)	tie	55 years	5 of 100 (Routine)
4 February 2011	San Juan, MX	daily low max	10.6 C (51.1 F)	1.1 C (2.0 F)	28 years	15 of 100 (Routine)
30 January 2011	San Juan, MX	daily high min	20.6 C (69.1 F)	0.6 C (1.1 F)	40 years	19 of 100 (Routine)

Climate Trend

44 complete years, 1951 to 2010

One stripe for each of 44 complete years at San Juan, 1951 to 2010. Blue stripes are years cooler than the station's own mean of 22.9 C (73.1 F); red stripes are warmer. The coolest year was 1976, at 20.4 C (68.8 F), and the warmest was 1969, at 25.9 C (78.5 F). The strongest colour marks a difference of 3.1 C (5.6 F).

Annual mean temperature at San Juan as warming stripes, 1951 to 2010
Year	Annual mean temperature	Difference from the station mean
1951	23.2 C	+0.30 C
1952	22.4 C	-0.45 C
1953	23.7 C	+0.88 C
1954	23.7 C	+0.81 C
1955	22.7 C	-0.11 C
1956	23.4 C	+0.56 C
1957	23.3 C	+0.40 C
1958	23.5 C	+0.67 C
1959	23.9 C	+1.05 C
1965	23.3 C	+0.42 C
1966	23.1 C	+0.26 C
1968	23.1 C	+0.27 C
1969	25.9 C	+3.01 C
1970	22.1 C	-0.75 C
1971	23.8 C	+0.90 C
1973	21.4 C	-1.46 C
1975	21.9 C	-0.92 C
1976	20.4 C	-2.41 C
1977	22.1 C	-0.77 C
1979	22.1 C	-0.76 C
1980	22.7 C	-0.14 C
1981	21.7 C	-1.19 C
1982	22.1 C	-0.72 C
1983	21.4 C	-1.49 C
1985	22.8 C	-0.06 C
1986	22.9 C	+0.04 C
1987	22.0 C	-0.85 C
1988	22.4 C	-0.46 C
1989	22.9 C	+0.09 C
1990	23.6 C	+0.73 C
1991	23.2 C	+0.37 C
1992	22.9 C	+0.03 C
1993	22.8 C	-0.05 C
1994	23.5 C	+0.65 C
1996	24.2 C	+1.32 C
1997	22.3 C	-0.54 C
1998	24.1 C	+1.24 C
1999	23.6 C	+0.73 C
2001	23.3 C	+0.42 C
2002	22.8 C	-0.04 C
2004	22.1 C	-0.80 C
2005	22.6 C	-0.25 C
2008	22.8 C	-0.05 C
2010	22.1 C	-0.72 C

The fitted trend in annual mean temperature here over 1951 to 2010 is -0.1 C (-0.2 to 0.1) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: -0.1 F (-0.4 to 0.1) per decade. The slope is a straight line fitted to 44 complete years; the brackets give its 95 percent interval.

Fitted temperature trends per decade at San Juan
Measure	Per decade (C)	Per decade (F)	Period	Complete years	Reading
Annual mean temperature	-0.1 C (-0.2 to 0.1) per decade	-0.1 F (-0.4 to 0.1) per decade	1951 to 2010	44	Not clearly different from zero
Mean daily maximum	-0.2 C (-0.5 to 0.1) per decade	-0.4 F (-0.9 to 0.1) per decade	1951 to 2010	44	Not clearly different from zero
Mean daily minimum	0.1 C (-0.1 to 0.2) per decade	0.1 F (-0.2 to 0.4) per decade	1951 to 2010	44	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

1947 to 2011

Yearly extremes at San Juan: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	46.1 C (115.0 F)	1998	42.2 C (108.0 F)	61
Coldest night (TNn)	-8.3 C (17.1 F)	1983	-2.2 C (28.0 F)	61
Wettest day (Rx1day)	170.2 mm (6.7 in)	1988	77.7 mm (3.1 in)	64
Wettest five days (Rx5day)	456.7 mm (18.0 in)	1973	133.0 mm (5.2 in)	64
Longest dry spell (CDD)	118 days	2011	47 days	64

Hottest day (TXx)

The hottest day of the year at San Juan, 1947 to 2011. The record is 46.1 C (115.0 F) in 1998, marked on the chart; the median year is 42.2 C (108.0 F).

Hottest day (TXx) at San Juan by year
Year	Hottest day (TXx)
1947	n/a
1948	n/a
1949	n/a
1950	38.9 C (102.0 F)
1951	43.3 C (109.9 F)
1952	41.7 C (107.1 F)
1953	45.0 C (113.0 F)
1954	43.9 C (111.0 F)
1955	43.9 C (111.0 F)
1956	41.7 C (107.1 F)
1957	43.3 C (109.9 F)
1958	45.0 C (113.0 F)
1959	41.7 C (107.1 F)
1960	41.7 C (107.1 F)
1961	35.0 C (95.0 F)
1962	38.9 C (102.0 F)
1963	45.0 C (113.0 F)
1964	41.1 C (106.0 F)
1965	41.1 C (106.0 F)
1966	42.2 C (108.0 F)
1967	42.2 C (108.0 F)
1968	40.6 C (105.1 F)
1969	40.6 C (105.1 F)
1970	41.1 C (106.0 F)
1971	40.0 C (104.0 F)
1972	41.7 C (107.1 F)
1973	43.9 C (111.0 F)
1974	42.8 C (109.0 F)
1975	40.6 C (105.1 F)
1976	38.9 C (102.0 F)
1977	40.6 C (105.1 F)
1978	41.7 C (107.1 F)
1979	42.2 C (108.0 F)
1980	41.7 C (107.1 F)
1981	41.7 C (107.1 F)
1982	42.2 C (108.0 F)
1983	43.9 C (111.0 F)
1984	43.9 C (111.0 F)
1985	40.0 C (104.0 F)
1986	42.2 C (108.0 F)
1987	40.6 C (105.1 F)
1988	42.8 C (109.0 F)
1989	42.2 C (108.0 F)
1990	43.3 C (109.9 F)
1991	42.8 C (109.0 F)
1992	44.4 C (111.9 F)
1993	40.6 C (105.1 F)
1994	42.2 C (108.0 F)
1995	43.9 C (111.0 F)
1996	43.3 C (109.9 F)
1997	44.4 C (111.9 F)
1998	46.1 C (115.0 F)
1999	42.2 C (108.0 F)
2000	41.7 C (107.1 F)
2001	44.4 C (111.9 F)
2002	45.0 C (113.0 F)
2003	41.7 C (107.1 F)
2004	45.0 C (113.0 F)
2005	45.0 C (113.0 F)
2006	45.6 C (114.1 F)
2008	41.7 C (107.1 F)
2009	41.7 C (107.1 F)
2010	40.0 C (104.0 F)
2011	45.0 C (113.0 F)

Coldest night (TNn)

The coldest night of the year at San Juan, 1947 to 2011. The record is -8.3 C (17.1 F) in 1983, marked on the chart; the median year is -2.2 C (28.0 F).

Coldest night (TNn) at San Juan by year
Year	Coldest night (TNn)
1947	n/a
1948	n/a
1949	n/a
1950	0.0 C (32.0 F)
1951	0.0 C (32.0 F)
1952	-4.4 C (24.1 F)
1953	-5.0 C (23.0 F)
1954	0.0 C (32.0 F)
1955	-4.4 C (24.1 F)
1956	-4.4 C (24.1 F)
1957	-5.0 C (23.0 F)
1958	0.0 C (32.0 F)
1959	-2.2 C (28.0 F)
1960	-5.6 C (21.9 F)
1961	-2.2 C (28.0 F)
1962	-3.3 C (26.1 F)
1963	-3.9 C (25.0 F)
1964	1.7 C (35.1 F)
1965	0.6 C (33.1 F)
1966	-2.2 C (28.0 F)
1967	-4.4 C (24.1 F)
1968	1.7 C (35.1 F)
1969	0.0 C (32.0 F)
1970	3.9 C (39.0 F)
1971	0.6 C (33.1 F)
1972	0.0 C (32.0 F)
1973	-5.0 C (23.0 F)
1974	-3.3 C (26.1 F)
1975	-4.4 C (24.1 F)
1976	-5.0 C (23.0 F)
1977	-4.4 C (24.1 F)
1978	-3.3 C (26.1 F)
1979	-3.9 C (25.0 F)
1980	-1.1 C (30.0 F)
1981	0.0 C (32.0 F)
1982	-3.3 C (26.1 F)
1983	-8.3 C (17.1 F)
1984	-6.1 C (21.0 F)
1985	-6.1 C (21.0 F)
1986	-2.8 C (27.0 F)
1987	-2.2 C (28.0 F)
1988	-1.7 C (28.9 F)
1989	-2.8 C (27.0 F)
1990	-2.2 C (28.0 F)
1991	0.0 C (32.0 F)
1992	0.6 C (33.1 F)
1993	-1.7 C (28.9 F)
1994	-1.7 C (28.9 F)
1995	1.7 C (35.1 F)
1996	-4.4 C (24.1 F)
1997	-3.9 C (25.0 F)
1998	-3.3 C (26.1 F)
1999	-3.9 C (25.0 F)
2000	-1.1 C (30.0 F)
2001	-3.3 C (26.1 F)
2002	-1.1 C (30.0 F)
2003	-1.1 C (30.0 F)
2004	-6.1 C (21.0 F)
2005	-2.2 C (28.0 F)
2006	0.0 C (32.0 F)
2008	0.6 C (33.1 F)
2009	3.9 C (39.0 F)
2010	-4.4 C (24.1 F)
2011	-3.3 C (26.1 F)

Wettest day (Rx1day)

The wettest day of the year at San Juan, 1947 to 2011. The record is 170.2 mm (6.7 in) in 1988, marked on the chart; the median year is 77.7 mm (3.1 in).

Wettest day (Rx1day) at San Juan by year
Year	Wettest day (Rx1day)
1947	56.1 mm (2.2 in)
1948	136.4 mm (5.4 in)
1949	66.5 mm (2.6 in)
1950	132.3 mm (5.2 in)
1951	89.9 mm (3.5 in)
1952	41.9 mm (1.6 in)
1953	87.9 mm (3.5 in)
1954	129.8 mm (5.1 in)
1955	57.9 mm (2.3 in)
1956	37.8 mm (1.5 in)
1957	64.8 mm (2.6 in)
1958	99.8 mm (3.9 in)
1959	34.3 mm (1.4 in)
1960	3.8 mm (0.15 in)
1961	95.0 mm (3.7 in)
1962	45.0 mm (1.8 in)
1963	58.9 mm (2.3 in)
1964	87.9 mm (3.5 in)
1965	49.3 mm (1.9 in)
1966	46.5 mm (1.8 in)
1967	83.8 mm (3.3 in)
1968	116.8 mm (4.6 in)
1969	74.9 mm (2.9 in)
1970	118.9 mm (4.7 in)
1971	70.9 mm (2.8 in)
1972	64.8 mm (2.6 in)
1973	130.3 mm (5.1 in)
1974	81.8 mm (3.2 in)
1975	52.8 mm (2.1 in)
1976	99.8 mm (3.9 in)
1977	66.8 mm (2.6 in)
1978	85.9 mm (3.4 in)
1979	143.3 mm (5.6 in)
1980	49.8 mm (2.0 in)
1981	100.1 mm (3.9 in)
1982	54.9 mm (2.2 in)
1983	143.8 mm (5.7 in)
1984	63.8 mm (2.5 in)
1985	111.3 mm (4.4 in)
1986	132.8 mm (5.2 in)
1987	68.6 mm (2.7 in)
1988	170.2 mm (6.7 in)
1989	71.1 mm (2.8 in)
1990	59.4 mm (2.3 in)
1991	64.8 mm (2.6 in)
1992	56.1 mm (2.2 in)
1993	81.3 mm (3.2 in)
1994	61.0 mm (2.4 in)
1995	97.8 mm (3.9 in)
1996	64.3 mm (2.5 in)
1997	85.1 mm (3.4 in)
1998	91.9 mm (3.6 in)
1999	85.3 mm (3.4 in)
2000	129.8 mm (5.1 in)
2001	80.5 mm (3.2 in)
2002	72.9 mm (2.9 in)
2003	111.8 mm (4.4 in)
2004	63.8 mm (2.5 in)
2005	134.9 mm (5.3 in)
2006	51.8 mm (2.0 in)
2008	39.9 mm (1.6 in)
2009	23.9 mm (0.9 in)
2010	160.8 mm (6.3 in)
2011	99.8 mm (3.9 in)

Wettest five days (Rx5day)

The wettest five days of the year at San Juan, 1947 to 2011. The record is 456.7 mm (18.0 in) in 1973, marked on the chart; the median year is 133.0 mm (5.2 in).

Wettest five days (Rx5day) at San Juan by year
Year	Wettest five days (Rx5day)
1947	151.6 mm (6.0 in)
1948	198.4 mm (7.8 in)
1949	75.9 mm (3.0 in)
1950	132.3 mm (5.2 in)
1951	161.0 mm (6.3 in)
1952	71.4 mm (2.8 in)
1953	230.9 mm (9.1 in)
1954	132.6 mm (5.2 in)
1955	120.4 mm (4.7 in)
1956	64.2 mm (2.5 in)
1957	84.6 mm (3.3 in)
1958	249.5 mm (9.8 in)
1959	63.5 mm (2.5 in)
1960	3.8 mm (0.15 in)
1961	95.0 mm (3.7 in)
1962	66.6 mm (2.6 in)
1963	96.5 mm (3.8 in)
1964	133.4 mm (5.3 in)
1965	93.8 mm (3.7 in)
1966	99.1 mm (3.9 in)
1967	258.3 mm (10.2 in)
1968	247.6 mm (9.7 in)
1969	159.5 mm (6.3 in)
1970	152.5 mm (6.0 in)
1971	118.9 mm (4.7 in)
1972	184.5 mm (7.3 in)
1973	456.7 mm (18.0 in)
1974	171.2 mm (6.7 in)
1975	134.8 mm (5.3 in)
1976	196.9 mm (7.8 in)
1977	110.5 mm (4.4 in)
1978	168.4 mm (6.6 in)
1979	158.3 mm (6.2 in)
1980	86.6 mm (3.4 in)
1981	250.2 mm (9.9 in)
1982	71.2 mm (2.8 in)
1983	173.8 mm (6.8 in)
1984	75.0 mm (3.0 in)
1985	152.5 mm (6.0 in)
1986	177.5 mm (7.0 in)
1987	196.1 mm (7.7 in)
1988	191.6 mm (7.5 in)
1989	76.7 mm (3.0 in)
1990	71.0 mm (2.8 in)
1991	129.0 mm (5.1 in)
1992	65.0 mm (2.6 in)
1993	120.4 mm (4.7 in)
1994	73.7 mm (2.9 in)
1995	237.5 mm (9.4 in)
1996	109.0 mm (4.3 in)
1997	165.3 mm (6.5 in)
1998	103.9 mm (4.1 in)
1999	182.9 mm (7.2 in)
2000	183.6 mm (7.2 in)
2001	156.0 mm (6.1 in)
2002	132.6 mm (5.2 in)
2003	179.1 mm (7.1 in)
2004	93.5 mm (3.7 in)
2005	232.5 mm (9.2 in)
2006	116.3 mm (4.6 in)
2008	139.5 mm (5.5 in)
2009	45.7 mm (1.8 in)
2010	330.5 mm (13.0 in)
2011	118.9 mm (4.7 in)

Longest dry spell (CDD)

The longest dry spell of the year at San Juan, 1947 to 2011. The record is 118 days in 2011, marked on the chart; the median year is 47 days.

Longest dry spell (CDD) at San Juan by year
Year	Longest dry spell (CDD)
1947	33 days
1948	46 days
1949	33 days
1950	61 days
1951	30 days
1952	61 days
1953	46 days
1954	57 days
1955	31 days
1956	31 days
1957	58 days
1958	49 days
1959	78 days
1960	83 days
1961	56 days
1962	74 days
1963	71 days
1964	49 days
1965	54 days
1966	75 days
1967	75 days
1968	57 days
1969	90 days
1970	72 days
1971	65 days
1972	31 days
1973	57 days
1974	45 days
1975	48 days
1976	28 days
1977	37 days
1978	32 days
1979	54 days
1980	43 days
1981	27 days
1982	49 days
1983	47 days
1984	12 days
1985	31 days
1986	28 days
1987	34 days
1988	38 days
1989	45 days
1990	45 days
1991	30 days
1992	74 days
1993	66 days
1994	24 days
1995	31 days
1996	59 days
1997	19 days
1998	83 days
1999	59 days
2000	29 days
2001	27 days
2002	43 days
2003	26 days
2004	31 days
2005	47 days
2006	48 days
2008	41 days
2009	33 days
2010	96 days
2011	118 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

21 years with a frost

Across 21 years with a frost, the median last spring frost at San Juan falls on 14 February and the median first autumn frost on 13 December, which leaves a median of 304 days between them.

Frost dates and growing season at San Juan
Measure	Median, all years	Earliest period	Recent period (1951 to 2010)	Recent against earliest	Fitted trend
Last spring frost	14 February	n/a	14 February	n/a	n/a
First autumn frost	13 December	n/a	13 December	n/a	n/a
Growing days	304 days	n/a	304 days	n/a	n/a

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

56 years, 1948 to 2010

A day with at least 78.0 mm (3.1 in) of rain is expected about once in 2 years. A day with at least 197.0 mm (7.8 in) of rain is expected about once in 100 years.

Rainfall return levels at San Juan: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	78.0 mm (3.1 in)
5 years	108.7 mm (4.3 in)
10 years	129.5 mm (5.1 in)
25 years	156.3 mm (6.2 in)
50 years	176.6 mm (7.0 in)
100 years	197.0 mm (7.8 in)	Longer than the 56 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, 56 years of values from 1948 to 2010.

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: 170.2 mm (6.7 in) in 1988; 160.8 mm (6.3 in) in 2010; 143.8 mm (5.7 in) in 1983.

Station Changes

No change in the annual mean temperature of this station was found against its neighbours.

Download the Data

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