Chalco -San Lucas- Weather Records (MXN00015020)
Record envelope, standing records and threshold days for Chalco -San Lucas- (MXN00015020), Mexico, with 52 years of record.
Key Facts for Chalco -San Lucas-
- Chalco -San Lucas- (MXN00015020) is a weather station in Mexico at 19.25 latitude and -98.88 longitude, 2,240 m (7,349 ft) above sea level.
- The station reports from 1961 to 2012, 52 years of record.
- 1,464 records set at Chalco -San Lucas- still stand.
- Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.
- Chalco -San Lucas- tied a daily record low maximum temperature of 17.8 C (64.0 F) on 22 July 2012.
About the Station
- Location: Mexico, 19.25 latitude, -98.88 longitude.
- Elevation: 2,240 m (7,349 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| Month | Highest record high | Lowest record low | 2026 highest maximum | 2026 lowest minimum |
|---|---|---|---|---|
| Jan | 28.9 C (84.0 F) | -9.4 C (15.1 F) | n/a | n/a |
| Feb | 27.8 C (82.0 F) | -10.0 C (14.0 F) | n/a | n/a |
| Mar | 36.7 C (98.1 F) | -4.4 C (24.1 F) | n/a | n/a |
| Apr | 32.2 C (90.0 F) | -4.4 C (24.1 F) | n/a | n/a |
| May | 33.9 C (93.0 F) | 0.0 C (32.0 F) | n/a | n/a |
| Jun | 33.9 C (93.0 F) | 2.2 C (36.0 F) | n/a | n/a |
| Jul | 32.8 C (91.0 F) | 3.3 C (37.9 F) | n/a | n/a |
| Aug | 28.9 C (84.0 F) | 1.7 C (35.1 F) | n/a | n/a |
| Sep | 27.8 C (82.0 F) | -1.7 C (28.9 F) | n/a | n/a |
| Oct | 27.8 C (82.0 F) | -4.4 C (24.1 F) | n/a | n/a |
| Nov | 27.8 C (82.0 F) | -7.2 C (19.0 F) | n/a | n/a |
| Dec | 26.7 C (80.1 F) | -8.3 C (17.1 F) | n/a | n/a |
Which Years Hold Standing Records
1,464 standing records| Year set | Standing records |
|---|---|
| 1967 | 35 |
| 1968 | 36 |
| 1969 | 68 |
| 1970 | 47 |
| 1971 | 50 |
| 1972 | 78 |
| 1973 | 92 |
| 1974 | 46 |
| 1975 | 23 |
| 1976 | 51 |
| 1977 | 35 |
| 1978 | 32 |
| 1979 | 46 |
| 1980 | 43 |
| 1981 | 18 |
| 1982 | 69 |
| 1983 | 55 |
| 1984 | 19 |
| 1985 | 20 |
| 1986 | 29 |
| 1987 | 43 |
| 1988 | 17 |
| 1993 | 79 |
| 1995 | 17 |
| 1996 | 8 |
| 1997 | 23 |
| 1998 | 8 |
| 1999 | 19 |
| 2000 | 11 |
| 2001 | 3 |
| 2002 | 6 |
| 2003 | 5 |
| 2004 | 4 |
| 2005 | 14 |
| 2006 | 12 |
| 2007 | 13 |
| 2008 | 4 |
| 2009 | 20 |
| 2010 | 196 |
| 2011 | 43 |
| 2012 | 27 |
All-Time Record Progression
1 new records| Date | Kind | Detail |
|---|---|---|
| 2010-01-11 | Record low maximum temperature | Record low maximum temperature 3.9 C (39.0 F) |
Wettest Day of Each Month
May: 80.0 mm (3.1 in)| Month | Record daily precipitation (mm) | Date |
|---|---|---|
| Jan | 58.4 mm (2.3 in) | 10 January 1967 |
| Feb | 26.7 mm (1.1 in) | 3 February 2010 |
| Mar | 45.7 mm (1.8 in) | 4 March 1988 |
| Apr | 28.4 mm (1.1 in) | 3 April 1971 |
| May | 80.0 mm (3.1 in) | 29 May 1972 |
| Jun | 43.4 mm (1.7 in) | 16 June 1966 |
| Jul | 48.3 mm (1.9 in) | 7 July 2000 |
| Aug | 73.2 mm (2.9 in) | 31 August 1987 |
| Sep | 59.7 mm (2.4 in) | 12 September 1997 |
| Oct | 47.2 mm (1.9 in) | 11 October 2005 |
| Nov | 18.3 mm (0.7 in) | 14 November 2006 |
| Dec | 18.0 mm (0.7 in) | 10 December 1962 |
Period of Record Coverage
1967 to 2012| Year | Days with data | Share of year | Complete |
|---|---|---|---|
| 1967 | 295 | 81% | No |
| 1968 | 366 | 100% | Yes |
| 1969 | 361 | 99% | Yes |
| 1970 | 365 | 100% | Yes |
| 1971 | 365 | 100% | Yes |
| 1972 | 366 | 100% | Yes |
| 1973 | 365 | 100% | Yes |
| 1974 | 365 | 100% | Yes |
| 1975 | 365 | 100% | Yes |
| 1976 | 366 | 100% | Yes |
| 1977 | 364 | 100% | Yes |
| 1978 | 364 | 100% | 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 | 365 | 100% | Yes |
| 1986 | 365 | 100% | Yes |
| 1987 | 365 | 100% | Yes |
| 1988 | 366 | 100% | Yes |
| 1989 | 45 | 12% | No |
| 1990 | 74 | 20% | No |
| 1993 | 254 | 70% | No |
| 1995 | 228 | 62% | No |
| 1996 | 273 | 75% | No |
| 1997 | 365 | 100% | Yes |
| 1998 | 365 | 100% | Yes |
| 1999 | 364 | 100% | Yes |
| 2000 | 274 | 75% | No |
| 2001 | 358 | 98% | Yes |
| 2002 | 349 | 96% | Yes |
| 2003 | 358 | 98% | Yes |
| 2004 | 351 | 96% | Yes |
| 2005 | 338 | 93% | Yes |
| 2006 | 354 | 97% | Yes |
| 2007 | 345 | 95% | Yes |
| 2008 | 117 | 32% | No |
| 2009 | 333 | 91% | Yes |
| 2010 | 299 | 82% | No |
| 2011 | 343 | 94% | Yes |
| 2012 | 212 | 58% | No |
Latest Records
20| Date | Station | Record | Value | Beat old record by | Old record stood | Significance |
|---|---|---|---|---|---|---|
| 22 July 2012 | Chalco -San Lucas-, MX | daily low max (Tie) | 17.8 C (64.0 F) | tie | 24 years | 2 of 100 (Routine) |
| 17 July 2012 | Chalco -San Lucas-, MX | daily low min | 5.6 C (42.1 F) | 0.5 C (0.9 F) | 35 years | 16 of 100 (Routine) |
| 13 July 2012 | Chalco -San Lucas-, MX | daily low min | 5.0 C (41.0 F) | 0.6 C (1.1 F) | 12 years | 9 of 100 (Routine) |
| 27 June 2012 | Chalco -San Lucas-, MX | daily low min (Tie) | 5.6 C (42.1 F) | tie | 1 year | 1 of 100 (Routine) |
| 24 June 2012 | Chalco -San Lucas-, MX | daily low min | 5.6 C (42.1 F) | 1.1 C (2.0 F) | 33 years | 17 of 100 (Routine) |
| 17 June 2012 | Chalco -San Lucas-, MX | daily low min (Tie) | 5.6 C (42.1 F) | tie | 30 years | 3 of 100 (Routine) |
| 17 May 2012 | Chalco -San Lucas-, MX | daily low min (Tie) | 5.0 C (41.0 F) | tie | 25 years | 2 of 100 (Routine) |
| 16 May 2012 | Chalco -San Lucas-, MX | monthly low max (Tie) | 16.7 C (62.1 F) | tie | 19 years | 4 of 100 (Routine) |
| 13 May 2012 | Chalco -San Lucas-, MX | daily low max | 17.8 C (64.0 F) | 1.6 C (2.9 F) | 19 years | 14 of 100 (Routine) |
| 10 May 2012 | Chalco -San Lucas-, MX | monthly low max (Tie) | 16.7 C (62.1 F) | tie | 18 years | 4 of 100 (Routine) |
| 7 May 2012 | Chalco -San Lucas-, MX | daily low max | 17.8 C (64.0 F) | 3.9 C (7.0 F) | 8 years | 20 of 100 (Routine) |
| 6 May 2012 | Chalco -San Lucas-, MX | daily low max | 20.0 C (68.0 F) | 1.7 C (3.1 F) | 27 years | 18 of 100 (Routine) |
| 5 May 2012 | Chalco -San Lucas-, MX | daily high min | 14.4 C (57.9 F) | 2.2 C (4.0 F) | 19 years | 18 of 100 (Routine) |
| 3 May 2012 | Chalco -San Lucas-, MX | daily high min | 12.8 C (55.0 F) | 1.1 C (2.0 F) | 7 years | 10 of 100 (Routine) |
| 1 May 2012 | Chalco -San Lucas-, MX | daily high min | 12.2 C (54.0 F) | 0.5 C (0.9 F) | 7 years | 8 of 100 (Routine) |
| 30 April 2012 | Chalco -San Lucas-, MX | daily high min (Tie) | 12.8 C (55.0 F) | tie | 42 years | 4 of 100 (Routine) |
| 29 April 2012 | Chalco -San Lucas-, MX | daily high min (Tie) | 11.7 C (53.1 F) | tie | 42 years | 4 of 100 (Routine) |
| 28 April 2012 | Chalco -San Lucas-, MX | daily high min | 12.2 C (54.0 F) | 0.5 C (0.9 F) | 39 years | 17 of 100 (Routine) |
| 24 April 2012 | Chalco -San Lucas-, MX | daily low max (Tie) | 20.0 C (68.0 F) | tie | 28 years | 3 of 100 (Routine) |
| 18 April 2012 | Chalco -San Lucas-, MX | daily low max (Tie) | 20.0 C (68.0 F) | tie | 13 years | 1 of 100 (Routine) |
Climate Trend
27 complete years, 1968 to 2006| Year | Annual mean temperature | Difference from the station mean |
|---|---|---|
| 1968 | 14.9 C | +0.25 C |
| 1969 | 15.7 C | +1.06 C |
| 1970 | 15.3 C | +0.70 C |
| 1971 | 14.9 C | +0.30 C |
| 1972 | 15.4 C | +0.73 C |
| 1973 | 15.4 C | +0.73 C |
| 1974 | 14.9 C | +0.30 C |
| 1975 | 15.3 C | +0.62 C |
| 1976 | 15.1 C | +0.46 C |
| 1977 | 14.4 C | -0.25 C |
| 1978 | 14.4 C | -0.25 C |
| 1979 | 14.3 C | -0.36 C |
| 1980 | 14.5 C | -0.09 C |
| 1981 | 14.6 C | +0.00 C |
| 1982 | 14.7 C | +0.11 C |
| 1983 | 14.6 C | -0.05 C |
| 1984 | 14.0 C | -0.64 C |
| 1985 | 14.2 C | -0.42 C |
| 1986 | 14.4 C | -0.25 C |
| 1987 | 14.5 C | -0.14 C |
| 1988 | 14.1 C | -0.52 C |
| 1997 | 14.5 C | -0.18 C |
| 1998 | 14.0 C | -0.60 C |
| 1999 | 14.0 C | -0.64 C |
| 2001 | 14.1 C | -0.53 C |
| 2003 | 14.7 C | +0.06 C |
| 2006 | 14.2 C | -0.42 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
1961 to 2012| Measure | Record | Year of the record | Median year | Years with a value |
|---|---|---|---|---|
| Hottest day (TXx) | 36.7 C (98.1 F) | 1985 | 29.4 C (84.9 F) | 43 |
| Coldest night (TNn) | -10.0 C (14.0 F) | 1973 | -4.4 C (24.1 F) | 43 |
| Wettest day (Rx1day) | 80.0 mm (3.1 in) | 1972 | 35.8 mm (1.4 in) | 49 |
| Wettest five days (Rx5day) | 106.7 mm (4.2 in) | 1972 | 62.7 mm (2.5 in) | 49 |
| Longest dry spell (CDD) | 134 days | 1998 | 64 days | 49 |
Hottest day (TXx)
| Year | Hottest day (TXx) |
|---|---|
| 1961 | n/a |
| 1962 | n/a |
| 1963 | n/a |
| 1964 | n/a |
| 1965 | n/a |
| 1966 | n/a |
| 1967 | 30.6 C (87.1 F) |
| 1968 | 27.8 C (82.0 F) |
| 1969 | 33.9 C (93.0 F) |
| 1970 | 30.0 C (86.0 F) |
| 1971 | 30.0 C (86.0 F) |
| 1972 | 30.6 C (87.1 F) |
| 1973 | 33.9 C (93.0 F) |
| 1974 | 30.6 C (87.1 F) |
| 1975 | 30.6 C (87.1 F) |
| 1976 | 30.0 C (86.0 F) |
| 1977 | 29.4 C (84.9 F) |
| 1978 | 32.2 C (90.0 F) |
| 1979 | 29.4 C (84.9 F) |
| 1980 | 29.4 C (84.9 F) |
| 1981 | 30.0 C (86.0 F) |
| 1982 | 32.8 C (91.0 F) |
| 1983 | 32.8 C (91.0 F) |
| 1984 | 31.1 C (88.0 F) |
| 1985 | 36.7 C (98.1 F) |
| 1986 | 30.6 C (87.1 F) |
| 1987 | 30.0 C (86.0 F) |
| 1988 | 30.0 C (86.0 F) |
| 1989 | 23.9 C (75.0 F) |
| 1990 | 26.1 C (79.0 F) |
| 1993 | 25.0 C (77.0 F) |
| 1995 | 26.7 C (80.1 F) |
| 1996 | 32.8 C (91.0 F) |
| 1997 | 27.8 C (82.0 F) |
| 1998 | 28.3 C (82.9 F) |
| 1999 | 28.3 C (82.9 F) |
| 2000 | 27.8 C (82.0 F) |
| 2001 | 28.9 C (84.0 F) |
| 2002 | 28.3 C (82.9 F) |
| 2003 | 28.9 C (84.0 F) |
| 2004 | 26.7 C (80.1 F) |
| 2005 | 29.4 C (84.9 F) |
| 2006 | 28.9 C (84.0 F) |
| 2007 | 28.9 C (84.0 F) |
| 2008 | 26.7 C (80.1 F) |
| 2009 | 27.2 C (81.0 F) |
| 2010 | 27.2 C (81.0 F) |
| 2011 | 27.8 C (82.0 F) |
| 2012 | 27.8 C (82.0 F) |
Coldest night (TNn)
| Year | Coldest night (TNn) |
|---|---|
| 1961 | n/a |
| 1962 | n/a |
| 1963 | n/a |
| 1964 | n/a |
| 1965 | n/a |
| 1966 | n/a |
| 1967 | -1.1 C (30.0 F) |
| 1968 | -3.3 C (26.1 F) |
| 1969 | -3.3 C (26.1 F) |
| 1970 | -4.4 C (24.1 F) |
| 1971 | -7.2 C (19.0 F) |
| 1972 | -8.3 C (17.1 F) |
| 1973 | -10.0 C (14.0 F) |
| 1974 | -6.1 C (21.0 F) |
| 1975 | -6.1 C (21.0 F) |
| 1976 | -7.2 C (19.0 F) |
| 1977 | -5.0 C (23.0 F) |
| 1978 | -5.0 C (23.0 F) |
| 1979 | -3.9 C (25.0 F) |
| 1980 | -5.6 C (21.9 F) |
| 1981 | -5.0 C (23.0 F) |
| 1982 | -5.6 C (21.9 F) |
| 1983 | -6.1 C (21.0 F) |
| 1984 | -5.0 C (23.0 F) |
| 1985 | -4.4 C (24.1 F) |
| 1986 | -3.9 C (25.0 F) |
| 1987 | -7.2 C (19.0 F) |
| 1988 | -6.1 C (21.0 F) |
| 1989 | -1.7 C (28.9 F) |
| 1990 | 1.1 C (34.0 F) |
| 1993 | -1.1 C (30.0 F) |
| 1995 | -2.2 C (28.0 F) |
| 1996 | -1.1 C (30.0 F) |
| 1997 | -7.2 C (19.0 F) |
| 1998 | -2.2 C (28.0 F) |
| 1999 | -5.0 C (23.0 F) |
| 2000 | -4.4 C (24.1 F) |
| 2001 | -1.7 C (28.9 F) |
| 2002 | -7.2 C (19.0 F) |
| 2003 | -4.4 C (24.1 F) |
| 2004 | -2.2 C (28.0 F) |
| 2005 | 0.0 C (32.0 F) |
| 2006 | -3.3 C (26.1 F) |
| 2007 | -3.3 C (26.1 F) |
| 2008 | 0.6 C (33.1 F) |
| 2009 | 0.6 C (33.1 F) |
| 2010 | -3.3 C (26.1 F) |
| 2011 | -5.0 C (23.0 F) |
| 2012 | 0.0 C (32.0 F) |
Wettest day (Rx1day)
| Year | Wettest day (Rx1day) |
|---|---|
| 1961 | 33.5 mm (1.3 in) |
| 1962 | 38.4 mm (1.5 in) |
| 1963 | 24.4 mm (1.0 in) |
| 1964 | 25.4 mm (1.0 in) |
| 1965 | 35.8 mm (1.4 in) |
| 1966 | 43.4 mm (1.7 in) |
| 1967 | 58.4 mm (2.3 in) |
| 1968 | 34.3 mm (1.4 in) |
| 1969 | 38.6 mm (1.5 in) |
| 1970 | 43.2 mm (1.7 in) |
| 1971 | 36.1 mm (1.4 in) |
| 1972 | 80.0 mm (3.1 in) |
| 1973 | 40.9 mm (1.6 in) |
| 1974 | 42.4 mm (1.7 in) |
| 1975 | 37.1 mm (1.5 in) |
| 1976 | 49.3 mm (1.9 in) |
| 1977 | 32.3 mm (1.3 in) |
| 1978 | 42.2 mm (1.7 in) |
| 1979 | 40.4 mm (1.6 in) |
| 1980 | 19.8 mm (0.8 in) |
| 1981 | 30.5 mm (1.2 in) |
| 1982 | 33.3 mm (1.3 in) |
| 1983 | 30.7 mm (1.2 in) |
| 1984 | 24.1 mm (0.9 in) |
| 1985 | 37.6 mm (1.5 in) |
| 1986 | 50.0 mm (2.0 in) |
| 1987 | 73.2 mm (2.9 in) |
| 1988 | 45.7 mm (1.8 in) |
| 1989 | 10.2 mm (0.4 in) |
| 1990 | 6.4 mm (0.25 in) |
| 1993 | 39.4 mm (1.6 in) |
| 1995 | 22.1 mm (0.9 in) |
| 1996 | 16.8 mm (0.7 in) |
| 1997 | 59.7 mm (2.4 in) |
| 1998 | 37.1 mm (1.5 in) |
| 1999 | 27.4 mm (1.1 in) |
| 2000 | 48.3 mm (1.9 in) |
| 2001 | 23.4 mm (0.9 in) |
| 2002 | 40.1 mm (1.6 in) |
| 2003 | 30.2 mm (1.2 in) |
| 2004 | 32.3 mm (1.3 in) |
| 2005 | 47.2 mm (1.9 in) |
| 2006 | 30.5 mm (1.2 in) |
| 2007 | 43.9 mm (1.7 in) |
| 2008 | 34.8 mm (1.4 in) |
| 2009 | 27.2 mm (1.1 in) |
| 2010 | 26.7 mm (1.1 in) |
| 2011 | 32.3 mm (1.3 in) |
| 2012 | 20.3 mm (0.8 in) |
Wettest five days (Rx5day)
| Year | Wettest five days (Rx5day) |
|---|---|
| 1961 | 68.0 mm (2.7 in) |
| 1962 | 66.0 mm (2.6 in) |
| 1963 | 50.3 mm (2.0 in) |
| 1964 | 60.9 mm (2.4 in) |
| 1965 | 72.4 mm (2.9 in) |
| 1966 | 72.0 mm (2.8 in) |
| 1967 | 90.7 mm (3.6 in) |
| 1968 | 78.4 mm (3.1 in) |
| 1969 | 68.9 mm (2.7 in) |
| 1970 | 68.4 mm (2.7 in) |
| 1971 | 73.4 mm (2.9 in) |
| 1972 | 106.7 mm (4.2 in) |
| 1973 | 62.7 mm (2.5 in) |
| 1974 | 57.9 mm (2.3 in) |
| 1975 | 63.3 mm (2.5 in) |
| 1976 | 75.2 mm (3.0 in) |
| 1977 | 55.9 mm (2.2 in) |
| 1978 | 64.5 mm (2.5 in) |
| 1979 | 60.1 mm (2.4 in) |
| 1980 | 51.5 mm (2.0 in) |
| 1981 | 49.0 mm (1.9 in) |
| 1982 | 50.6 mm (2.0 in) |
| 1983 | 51.3 mm (2.0 in) |
| 1984 | 48.7 mm (1.9 in) |
| 1985 | 68.4 mm (2.7 in) |
| 1986 | 65.4 mm (2.6 in) |
| 1987 | 92.5 mm (3.6 in) |
| 1988 | 78.7 mm (3.1 in) |
| 1989 | 10.2 mm (0.4 in) |
| 1990 | 9.5 mm (0.37 in) |
| 1993 | 94.6 mm (3.7 in) |
| 1995 | 48.8 mm (1.9 in) |
| 1996 | 32.1 mm (1.3 in) |
| 1997 | 70.4 mm (2.8 in) |
| 1998 | 74.2 mm (2.9 in) |
| 1999 | 52.1 mm (2.1 in) |
| 2000 | 93.5 mm (3.7 in) |
| 2001 | 42.9 mm (1.7 in) |
| 2002 | 56.0 mm (2.2 in) |
| 2003 | 62.2 mm (2.4 in) |
| 2004 | 85.7 mm (3.4 in) |
| 2005 | 57.9 mm (2.3 in) |
| 2006 | 60.6 mm (2.4 in) |
| 2007 | 56.2 mm (2.2 in) |
| 2008 | 75.3 mm (3.0 in) |
| 2009 | 55.7 mm (2.2 in) |
| 2010 | 58.2 mm (2.3 in) |
| 2011 | 73.5 mm (2.9 in) |
| 2012 | 38.7 mm (1.5 in) |
Longest dry spell (CDD)
| Year | Longest dry spell (CDD) |
|---|---|
| 1961 | 52 days |
| 1962 | 87 days |
| 1963 | 79 days |
| 1964 | 82 days |
| 1965 | 43 days |
| 1966 | 52 days |
| 1967 | 67 days |
| 1968 | 44 days |
| 1969 | 87 days |
| 1970 | 62 days |
| 1971 | 42 days |
| 1972 | 36 days |
| 1973 | 57 days |
| 1974 | 69 days |
| 1975 | 65 days |
| 1976 | 43 days |
| 1977 | 64 days |
| 1978 | 43 days |
| 1979 | 75 days |
| 1980 | 42 days |
| 1981 | 35 days |
| 1982 | 79 days |
| 1983 | 68 days |
| 1984 | 68 days |
| 1985 | 55 days |
| 1986 | 92 days |
| 1987 | 71 days |
| 1988 | 81 days |
| 1989 | 11 days |
| 1990 | 69 days |
| 1993 | 66 days |
| 1995 | 64 days |
| 1996 | 49 days |
| 1997 | 69 days |
| 1998 | 134 days |
| 1999 | 82 days |
| 2000 | 60 days |
| 2001 | 40 days |
| 2002 | 51 days |
| 2003 | 82 days |
| 2004 | 59 days |
| 2005 | 63 days |
| 2006 | 84 days |
| 2007 | 46 days |
| 2008 | 17 days |
| 2009 | 66 days |
| 2010 | 98 days |
| 2011 | 65 days |
| 2012 | 19 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
25 years with a frostAcross 25 years with a frost, the median last spring frost at Chalco -San Lucas- falls on 27 February and the median first autumn frost on 12 November, which leaves a median of 259 days between them.
Fitted over all years, the growing season changes by -4.2 days per decade at this station.
| Measure | Median, all years | Earliest period | Recent period (1969 to 2006) | Recent against earliest | Fitted trend |
|---|---|---|---|---|---|
| Last spring frost | 27 February | n/a | 27 February | n/a | +1.7 days per decade |
| First autumn frost | 12 November | n/a | 12 November | n/a | -2.5 days per decade |
| Growing days | 259 days | n/a | 259 days | n/a | -4.2 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
41 years, 1961 to 2011A day with at least 35.9 mm (1.4 in) of rain is expected about once in 2 years. A day with at least 82.2 mm (3.2 in) of rain is expected about once in 100 years.
| Expected about once in | A day with at least | Note |
|---|---|---|
| 2 years | 35.9 mm (1.4 in) | |
| 5 years | 46.6 mm (1.8 in) | |
| 10 years | 54.4 mm (2.1 in) | |
| 25 years | 64.9 mm (2.6 in) | |
| 50 years | 73.3 mm (2.9 in) | Longer than the 41 years of record |
| 100 years | 82.2 mm (3.2 in) | Longer than the 41 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, 41 years of values from 1961 to 2011.
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: 80.0 mm (3.1 in) in 1972; 73.2 mm (2.9 in) in 1987; 59.7 mm (2.4 in) in 1997.
Download the Data
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 . Last revised (2025-12-31).