Patillas Dam Weather Records (RQC00666904)

Record envelope, standing records and threshold days for Patillas Dam (RQC00666904), PR, Puerto Rico [United States], with 39 years of record.

Key Facts for Patillas Dam

Patillas Dam (RQC00666904) is a weather station in PR, Puerto Rico [United States] at 18.03 latitude and -66.03 longitude, 73 m (240 ft) above sea level.
The station reports from 1931 to 1969, 39 years of record.
1,464 records set at Patillas Dam still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
Patillas Dam tied a daily record low minimum temperature of 16.7 C (62.1 F) on 24 January 1969.

About the Station

Location: PR, Puerto Rico [United States], 18.03 latitude, -66.03 longitude.
Elevation: 73 m (240 ft).
Period of record: 1931 to 1969, 39 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 Patillas Dam. 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 Patillas Dam, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	32.2 C (90.0 F)	10.6 C (51.1 F)	n/a	n/a
Feb	33.9 C (93.0 F)	13.9 C (57.0 F)	n/a	n/a
Mar	32.8 C (91.0 F)	12.8 C (55.0 F)	n/a	n/a
Apr	37.2 C (99.0 F)	13.3 C (55.9 F)	n/a	n/a
May	33.9 C (93.0 F)	15.6 C (60.1 F)	n/a	n/a
Jun	36.1 C (97.0 F)	15.0 C (59.0 F)	n/a	n/a
Jul	33.9 C (93.0 F)	15.0 C (59.0 F)	n/a	n/a
Aug	36.7 C (98.1 F)	15.0 C (59.0 F)	n/a	n/a
Sep	39.4 C (102.9 F)	16.1 C (61.0 F)	n/a	n/a
Oct	37.2 C (99.0 F)	15.6 C (60.1 F)	n/a	n/a
Nov	35.0 C (95.0 F)	15.0 C (59.0 F)	n/a	n/a
Dec	32.8 C (91.0 F)	13.3 C (55.9 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Patillas Dam still stand. 1953 holds the most, with 120.

Standing records at Patillas Dam by the year they were set
Year set	Standing records
1937	43
1938	65
1939	99
1940	60
1941	22
1942	35
1943	27
1944	33
1945	71
1946	75
1947	67
1948	79
1949	75
1950	107
1951	65
1952	94
1953	120
1954	36
1955	29
1956	15
1957	39
1958	57
1959	47
1960	9
1961	8
1962	11
1963	16
1964	10
1965	11
1966	16
1967	9
1968	13
1969	1

Wettest Day of Each Month

Aug: 251.0 mm (9.9 in)

The wettest day on record for each calendar month at Patillas Dam. The most was 251.0 mm (9.9 in) on 4 August 1945.

Record daily precipitation for each month at Patillas Dam
Month	Record daily precipitation (mm)	Date
Jan	100.6 mm (4.0 in)	3 January 1937
Feb	91.4 mm (3.6 in)	3 February 1935
Mar	39.4 mm (1.6 in)	13 March 1960
Apr	235.2 mm (9.3 in)	28 April 1943
May	140.5 mm (5.5 in)	21 May 1936
Jun	113.3 mm (4.5 in)	1 June 1944
Jul	181.1 mm (7.1 in)	21 July 1958
Aug	251.0 mm (9.9 in)	4 August 1945
Sep	159.8 mm (6.3 in)	8 September 1953
Oct	188.0 mm (7.4 in)	11 October 1954
Nov	158.0 mm (6.2 in)	5 November 1942
Dec	130.8 mm (5.1 in)	3 December 1960

Period of Record Coverage

1937 to 1969

33 years of record at Patillas Dam, 1937 to 1969. 14 years have data for under 90 percent of days and are left out of rankings: 1937, 1940, 1951, 1959, 1960, 1961, 1962, 1963 and others.

Days with data per year at Patillas Dam
Year	Days with data	Share of year	Complete
1937	113	31%	No
1938	365	100%	Yes
1939	365	100%	Yes
1940	292	80%	No
1941	365	100%	Yes
1942	363	99%	Yes
1943	365	100%	Yes
1944	364	99%	Yes
1945	361	99%	Yes
1946	363	99%	Yes
1947	363	99%	Yes
1948	366	100%	Yes
1949	364	100%	Yes
1950	357	98%	Yes
1951	269	74%	No
1952	358	98%	Yes
1953	363	99%	Yes
1954	364	100%	Yes
1955	364	100%	Yes
1956	364	99%	Yes
1957	365	100%	Yes
1958	348	95%	Yes
1959	258	71%	No
1960	222	61%	No
1961	230	63%	No
1962	211	58%	No
1963	205	56%	No
1964	202	55%	No
1965	232	64%	No
1966	222	61%	No
1967	226	62%	No
1968	224	61%	No
1969	13	4%	No

Latest Records

Latest records at Patillas Dam
Date	Station	Record	Value	Beat old record by	Old record stood	Significance
24 January 1969	Patillas Dam, PR	daily low min (Tie)	16.7 C (62.1 F)	tie	24 years	2 of 100 (Routine)
16 January 1969	Patillas Dam, PR	daily rain	52.8 mm (2.1 in)	19.3 mm (0.8 in)	10 years	24 of 100 (Routine)
15 January 1969	Patillas Dam, PR	daily high max	31.1 C (88.0 F)	0.5 C (0.9 F)	30 years	15 of 100 (Routine)
13 December 1968	Patillas Dam, PR	daily high min	23.9 C (75.0 F)	0.6 C (1.1 F)	10 years	9 of 100 (Routine)
27 November 1968	Patillas Dam, PR	daily rain	38.1 mm (1.5 in)	5.6 mm (0.22 in)	3 years	6 of 100 (Routine)
20 November 1968	Patillas Dam, PR	daily rain	14.7 mm (0.6 in)	0.7 mm (0.03 in)	20 years	9 of 100 (Routine)
12 November 1968	Patillas Dam, PR	daily high max (Tie)	33.3 C (91.9 F)	tie	31 years	3 of 100 (Routine)
8 November 1968	Patillas Dam, PR	daily high max	33.3 C (91.9 F)	1.1 C (2.0 F)	26 years	16 of 100 (Routine)
4 November 1968	Patillas Dam, PR	daily high max	33.3 C (91.9 F)	1.1 C (2.0 F)	13 years	12 of 100 (Routine)
1 November 1968	Patillas Dam, PR	daily high max (Tie)	32.2 C (90.0 F)	tie	26 years	2 of 100 (Routine)
11 September 1968	Patillas Dam, PR	daily high min (Tie)	24.4 C (75.9 F)	tie	14 years	1 of 100 (Routine)
8 August 1968	Patillas Dam, PR	daily rain	54.1 mm (2.1 in)	0.3 mm (0.01 in)	15 years	7 of 100 (Routine)
7 August 1968	Patillas Dam, PR	daily rain	21.1 mm (0.8 in)	0.3 mm (0.01 in)	29 years	11 of 100 (Routine)
2 August 1968	Patillas Dam, PR	daily rain	55.4 mm (2.2 in)	12.0 mm (0.5 in)	5 years	10 of 100 (Routine)
18 June 1968	Patillas Dam, PR	daily high max (Tie)	31.1 C (88.0 F)	tie	26 years	2 of 100 (Routine)
4 June 1968	Patillas Dam, PR	daily rain	90.4 mm (3.6 in)	4.5 mm (0.18 in)	11 years	8 of 100 (Routine)
6 May 1968	Patillas Dam, PR	daily high min	26.1 C (79.0 F)	2.2 C (4.0 F)	9 years	16 of 100 (Routine)
23 April 1968	Patillas Dam, PR	daily low min	16.1 C (61.0 F)	1.1 C (2.0 F)	16 years	13 of 100 (Routine)
3 April 1968	Patillas Dam, PR	daily high max (Tie)	31.1 C (88.0 F)	tie	26 years	2 of 100 (Routine)
21 March 1968	Patillas Dam, PR	daily high max (Tie)	31.1 C (88.0 F)	tie	30 years	3 of 100 (Routine)

Climate Trend

19 complete years, 1938 to 1958

One stripe for each of 19 complete years at Patillas Dam, 1938 to 1958. Blue stripes are years cooler than the station's own mean of 25.1 C (77.1 F); red stripes are warmer. The coolest year was 1949, at 23.7 C (74.6 F), and the warmest was 1958, at 26.2 C (79.1 F). The strongest colour marks a difference of 1.5 C (2.7 F).

Annual mean temperature at Patillas Dam as warming stripes, 1938 to 1958
Year	Annual mean temperature	Difference from the station mean
1938	25.9 C	+0.82 C
1939	26.0 C	+0.89 C
1941	25.6 C	+0.56 C
1942	25.6 C	+0.50 C
1943	25.0 C	-0.08 C
1944	24.8 C	-0.32 C
1945	24.5 C	-0.53 C
1946	24.6 C	-0.52 C
1947	25.1 C	+0.03 C
1948	24.4 C	-0.65 C
1949	23.7 C	-1.41 C
1950	24.7 C	-0.40 C
1952	24.1 C	-0.99 C
1953	24.5 C	-0.59 C
1954	25.2 C	+0.10 C
1955	25.4 C	+0.34 C
1956	25.5 C	+0.38 C
1957	25.8 C	+0.70 C
1958	26.2 C	+1.08 C

This station does not have enough complete years (30 are needed) to fit a temperature trend.

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

1931 to 1969

Yearly extremes at Patillas Dam: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	39.4 C (102.9 F)	1945	33.9 C (93.0 F)	33
Coldest night (TNn)	10.6 C (51.1 F)	1951	15.6 C (60.1 F)	33
Wettest day (Rx1day)	251.0 mm (9.9 in)	1945	98.8 mm (3.9 in)	39
Wettest five days (Rx5day)	465.9 mm (18.3 in)	1954	203.0 mm (8.0 in)	39
Longest dry spell (CDD)	36 days	1935	18 days	39

Hottest day (TXx)

The hottest day of the year at Patillas Dam, 1931 to 1969. The record is 39.4 C (102.9 F) in 1945, marked on the chart; the median year is 33.9 C (93.0 F).

Hottest day (TXx) at Patillas Dam by year
Year	Hottest day (TXx)
1931	n/a
1932	n/a
1933	n/a
1934	n/a
1935	n/a
1936	n/a
1937	35.0 C (95.0 F)
1938	33.9 C (93.0 F)
1939	37.2 C (99.0 F)
1940	32.8 C (91.0 F)
1941	32.8 C (91.0 F)
1942	33.9 C (93.0 F)
1943	32.8 C (91.0 F)
1944	33.3 C (91.9 F)
1945	39.4 C (102.9 F)
1946	33.3 C (91.9 F)
1947	34.4 C (93.9 F)
1948	32.2 C (90.0 F)
1949	32.8 C (91.0 F)
1950	33.9 C (93.0 F)
1951	35.0 C (95.0 F)
1952	33.9 C (93.0 F)
1953	37.2 C (99.0 F)
1954	33.9 C (93.0 F)
1955	36.7 C (98.1 F)
1956	33.3 C (91.9 F)
1957	33.9 C (93.0 F)
1958	34.4 C (93.9 F)
1959	36.1 C (97.0 F)
1960	32.8 C (91.0 F)
1961	32.2 C (90.0 F)
1962	32.8 C (91.0 F)
1963	33.3 C (91.9 F)
1964	34.4 C (93.9 F)
1965	33.9 C (93.0 F)
1966	33.3 C (91.9 F)
1967	33.9 C (93.0 F)
1968	33.3 C (91.9 F)
1969	31.1 C (88.0 F)

Coldest night (TNn)

The coldest night of the year at Patillas Dam, 1931 to 1969. The record is 10.6 C (51.1 F) in 1951, marked on the chart; the median year is 15.6 C (60.1 F).

Coldest night (TNn) at Patillas Dam by year
Year	Coldest night (TNn)
1931	n/a
1932	n/a
1933	n/a
1934	n/a
1935	n/a
1936	n/a
1937	20.6 C (69.1 F)
1938	16.7 C (62.1 F)
1939	16.1 C (61.0 F)
1940	17.8 C (64.0 F)
1941	16.7 C (62.1 F)
1942	16.7 C (62.1 F)
1943	15.6 C (60.1 F)
1944	13.9 C (57.0 F)
1945	15.0 C (59.0 F)
1946	15.0 C (59.0 F)
1947	17.2 C (63.0 F)
1948	15.6 C (60.1 F)
1949	15.6 C (60.1 F)
1950	15.0 C (59.0 F)
1951	10.6 C (51.1 F)
1952	13.3 C (55.9 F)
1953	12.8 C (55.0 F)
1954	12.8 C (55.0 F)
1955	12.8 C (55.0 F)
1956	17.2 C (63.0 F)
1957	17.8 C (64.0 F)
1958	15.0 C (59.0 F)
1959	17.8 C (64.0 F)
1960	15.6 C (60.1 F)
1961	16.1 C (61.0 F)
1962	15.6 C (60.1 F)
1963	17.8 C (64.0 F)
1964	16.1 C (61.0 F)
1965	15.6 C (60.1 F)
1966	13.3 C (55.9 F)
1967	15.6 C (60.1 F)
1968	14.4 C (57.9 F)
1969	16.7 C (62.1 F)

Wettest day (Rx1day)

The wettest day of the year at Patillas Dam, 1931 to 1969. The record is 251.0 mm (9.9 in) in 1945, marked on the chart; the median year is 98.8 mm (3.9 in).

Wettest day (Rx1day) at Patillas Dam by year
Year	Wettest day (Rx1day)
1931	86.4 mm (3.4 in)
1932	113.5 mm (4.5 in)
1933	88.4 mm (3.5 in)
1934	62.2 mm (2.4 in)
1935	91.4 mm (3.6 in)
1936	140.5 mm (5.5 in)
1937	150.4 mm (5.9 in)
1938	106.7 mm (4.2 in)
1939	55.6 mm (2.2 in)
1940	121.7 mm (4.8 in)
1941	79.2 mm (3.1 in)
1942	158.0 mm (6.2 in)
1943	235.2 mm (9.3 in)
1944	138.4 mm (5.4 in)
1945	251.0 mm (9.9 in)
1946	63.8 mm (2.5 in)
1947	76.2 mm (3.0 in)
1948	110.7 mm (4.4 in)
1949	151.1 mm (5.9 in)
1950	99.6 mm (3.9 in)
1951	95.3 mm (3.8 in)
1952	98.8 mm (3.9 in)
1953	159.8 mm (6.3 in)
1954	188.0 mm (7.4 in)
1955	76.2 mm (3.0 in)
1956	93.0 mm (3.7 in)
1957	85.9 mm (3.4 in)
1958	181.1 mm (7.1 in)
1959	59.2 mm (2.3 in)
1960	130.8 mm (5.1 in)
1961	188.0 mm (7.4 in)
1962	148.1 mm (5.8 in)
1963	75.2 mm (3.0 in)
1964	88.6 mm (3.5 in)
1965	111.5 mm (4.4 in)
1966	83.8 mm (3.3 in)
1967	43.2 mm (1.7 in)
1968	90.4 mm (3.6 in)
1969	52.8 mm (2.1 in)

Wettest five days (Rx5day)

The wettest five days of the year at Patillas Dam, 1931 to 1969. The record is 465.9 mm (18.3 in) in 1954, marked on the chart; the median year is 203.0 mm (8.0 in).

Wettest five days (Rx5day) at Patillas Dam by year
Year	Wettest five days (Rx5day)
1931	270.0 mm (10.6 in)
1932	187.1 mm (7.4 in)
1933	264.6 mm (10.4 in)
1934	144.9 mm (5.7 in)
1935	184.4 mm (7.3 in)
1936	272.9 mm (10.7 in)
1937	259.8 mm (10.2 in)
1938	275.0 mm (10.8 in)
1939	101.1 mm (4.0 in)
1940	221.6 mm (8.7 in)
1941	134.6 mm (5.3 in)
1942	203.0 mm (8.0 in)
1943	396.7 mm (15.6 in)
1944	357.0 mm (14.1 in)
1945	288.8 mm (11.4 in)
1946	113.0 mm (4.4 in)
1947	158.3 mm (6.2 in)
1948	265.2 mm (10.4 in)
1949	281.3 mm (11.1 in)
1950	183.0 mm (7.2 in)
1951	185.5 mm (7.3 in)
1952	217.2 mm (8.6 in)
1953	211.5 mm (8.3 in)
1954	465.9 mm (18.3 in)
1955	153.1 mm (6.0 in)
1956	174.0 mm (6.9 in)
1957	149.9 mm (5.9 in)
1958	279.2 mm (11.0 in)
1959	119.4 mm (4.7 in)
1960	388.3 mm (15.3 in)
1961	208.9 mm (8.2 in)
1962	247.6 mm (9.7 in)
1963	123.2 mm (4.9 in)
1964	122.4 mm (4.8 in)
1965	226.6 mm (8.9 in)
1966	151.7 mm (6.0 in)
1967	68.3 mm (2.7 in)
1968	153.9 mm (6.1 in)
1969	53.6 mm (2.1 in)

Longest dry spell (CDD)

The longest dry spell of the year at Patillas Dam, 1931 to 1969. The record is 36 days in 1935, marked on the chart; the median year is 18 days.

Longest dry spell (CDD) at Patillas Dam by year
Year	Longest dry spell (CDD)
1931	21 days
1932	22 days
1933	16 days
1934	17 days
1935	36 days
1936	28 days
1937	19 days
1938	16 days
1939	19 days
1940	11 days
1941	21 days
1942	18 days
1943	15 days
1944	25 days
1945	17 days
1946	13 days
1947	18 days
1948	14 days
1949	26 days
1950	14 days
1951	36 days
1952	35 days
1953	19 days
1954	7 days
1955	22 days
1956	19 days
1957	15 days
1958	35 days
1959	15 days
1960	12 days
1961	12 days
1962	17 days
1963	12 days
1964	23 days
1965	13 days
1966	24 days
1967	26 days
1968	18 days
1969	5 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

37 years, 1931 to 1968

A day with at least 105.3 mm (4.1 in) of rain is expected about once in 2 years. A day with at least 291.4 mm (11.5 in) of rain is expected about once in 100 years.

Rainfall return levels at Patillas Dam: the daily rain expected about once in a given number of years
Expected about once in	A day with at least	Note
2 years	105.3 mm (4.1 in)
5 years	149.3 mm (5.9 in)
10 years	180.7 mm (7.1 in)
25 years	222.9 mm (8.8 in)
50 years	256.4 mm (10.1 in)	Longer than the 37 years of record
100 years	291.4 mm (11.5 in)	Longer than the 37 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, 37 years of values from 1931 to 1968.

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: 251.0 mm (9.9 in) in 1945; 235.2 mm (9.3 in) in 1943; 188.0 mm (7.4 in) in 1954.

Download the Data

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