Shelby AP Weather Records (USC00247501)

Record envelope, standing records and threshold days for Shelby AP (USC00247501), Montana, United States, with 31 years of record.

Key Facts for Shelby AP

Shelby AP (USC00247501) is a weather station in Montana, United States at 48.55 latitude and -111.87 longitude, 1,044 m (3,426 ft) above sea level.
The station reports from 1958 to 1988, 31 years of record.
1,464 records set at Shelby AP still stand.
Records are tracked for tmax, tmin, prcp: an element needs 30 years of data to be eligible.

About the Station

Location: Montana, United States, 48.55 latitude, -111.87 longitude.
Elevation: 1,044 m (3,426 ft).
Period of record: 1958 to 1988, 31 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 Shelby AP. 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 Shelby AP, with 2026 drawn through them
Month	Highest record high	Lowest record low	2026 highest maximum	2026 lowest minimum
Jan	17.2 C (63.0 F)	-38.3 C (-36.9 F)	n/a	n/a
Feb	20.6 C (69.1 F)	-32.8 C (-27.0 F)	n/a	n/a
Mar	22.2 C (72.0 F)	-33.9 C (-29.0 F)	n/a	n/a
Apr	31.1 C (88.0 F)	-20.6 C (-5.1 F)	n/a	n/a
May	32.8 C (91.0 F)	-10.0 C (14.0 F)	n/a	n/a
Jun	37.2 C (99.0 F)	-2.2 C (28.0 F)	n/a	n/a
Jul	38.9 C (102.0 F)	1.7 C (35.1 F)	n/a	n/a
Aug	41.1 C (106.0 F)	0.0 C (32.0 F)	n/a	n/a
Sep	36.1 C (97.0 F)	-8.3 C (17.1 F)	n/a	n/a
Oct	30.0 C (86.0 F)	-22.2 C (-8.0 F)	n/a	n/a
Nov	23.9 C (75.0 F)	-33.3 C (-27.9 F)	n/a	n/a
Dec	18.3 C (64.9 F)	-41.7 C (-43.1 F)	n/a	n/a

Which Years Hold Standing Records

1,464 standing records

1,464 records at Shelby AP still stand. 1969 holds the most, with 75.

Standing records at Shelby AP by the year they were set
Year set	Standing records
1958	14
1959	52
1960	55
1961	44
1962	56
1963	48
1964	37
1965	63
1966	42
1967	64
1968	48
1969	75
1970	26
1971	49
1972	68
1973	43
1974	42
1975	47
1976	40
1977	53
1978	21
1979	38
1980	46
1981	37
1982	29
1983	49
1984	56
1985	73
1986	56
1987	59
1988	34

Wettest Day of Each Month

Jun: 68.6 mm (2.7 in)

The wettest day on record for each calendar month at Shelby AP. The most was 68.6 mm (2.7 in) on 8 June 1964.

Record daily precipitation for each month at Shelby AP
Month	Record daily precipitation (mm)	Date
Jan	8.1 mm (0.32 in)	11 January 1972
Feb	12.4 mm (0.5 in)	29 February 1980
Mar	22.6 mm (0.9 in)	30 March 1981
Apr	21.6 mm (0.9 in)	23 April 1960
May	65.5 mm (2.6 in)	21 May 1981
Jun	68.6 mm (2.7 in)	8 June 1964
Jul	46.0 mm (1.8 in)	13 July 1970
Aug	38.1 mm (1.5 in)	24 August 1975
Sep	42.2 mm (1.7 in)	12 September 1985
Oct	19.1 mm (0.8 in)	11 October 1981
Nov	17.3 mm (0.7 in)	8 November 1985
Dec	13.5 mm (0.5 in)	12 December 1958

Period of Record Coverage

1958 to 1988

31 years of record at Shelby AP, 1958 to 1988. 3 years have data for under 90 percent of days and are left out of rankings: 1958, 1982, 1988.

Days with data per year at Shelby AP
Year	Days with data	Share of year	Complete
1958	167	46%	No
1959	343	94%	Yes
1960	362	99%	Yes
1961	353	97%	Yes
1962	359	98%	Yes
1963	364	100%	Yes
1964	364	99%	Yes
1965	364	100%	Yes
1966	364	100%	Yes
1967	362	99%	Yes
1968	366	100%	Yes
1969	364	100%	Yes
1970	361	99%	Yes
1971	365	100%	Yes
1972	365	100%	Yes
1973	364	100%	Yes
1974	364	100%	Yes
1975	365	100%	Yes
1976	363	99%	Yes
1977	365	100%	Yes
1978	365	100%	Yes
1979	363	99%	Yes
1980	366	100%	Yes
1981	363	99%	Yes
1982	328	90%	No
1983	363	99%	Yes
1984	365	100%	Yes
1985	362	99%	Yes
1986	363	99%	Yes
1987	358	98%	Yes
1988	243	66%	No

Latest Records

No records were set at this station in the latest data.

Climate Trend

28 complete years, 1959 to 1987

One stripe for each of 28 complete years at Shelby AP, 1959 to 1987. Blue stripes are years cooler than the station's own mean of 5.9 C (42.7 F); red stripes are warmer. The coolest year was 1978, at 4.1 C (39.4 F), and the warmest was 1987, at 8.2 C (46.8 F). The strongest colour marks a difference of 2.3 C (4.1 F).

Annual mean temperature at Shelby AP as warming stripes, 1959 to 1987
Year	Annual mean temperature	Difference from the station mean
1959	4.9 C	-1.04 C
1960	5.7 C	-0.21 C
1961	6.7 C	+0.80 C
1962	6.6 C	+0.71 C
1963	7.3 C	+1.34 C
1964	5.4 C	-0.55 C
1965	4.6 C	-1.31 C
1966	5.3 C	-0.66 C
1967	5.9 C	+0.00 C
1968	5.4 C	-0.49 C
1969	4.5 C	-1.44 C
1970	4.8 C	-1.16 C
1971	5.4 C	-0.52 C
1972	4.6 C	-1.30 C
1973	6.6 C	+0.67 C
1974	7.2 C	+1.26 C
1975	4.8 C	-1.18 C
1976	7.6 C	+1.71 C
1977	6.4 C	+0.45 C
1978	4.1 C	-1.83 C
1979	5.6 C	-0.30 C
1980	6.0 C	+0.11 C
1981	7.5 C	+1.60 C
1983	6.2 C	+0.29 C
1984	6.4 C	+0.48 C
1985	5.0 C	-0.91 C
1986	7.1 C	+1.14 C
1987	8.2 C	+2.27 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

1958 to 1988

Yearly extremes at Shelby AP: the record and the median year
Measure	Record	Year of the record	Median year	Years with a value
Hottest day (TXx)	41.1 C (106.0 F)	1961	36.1 C (97.0 F)	31
Coldest night (TNn)	-41.7 C (-43.1 F)	1983	-33.3 C (-27.9 F)	31
Wettest day (Rx1day)	68.6 mm (2.7 in)	1964	28.2 mm (1.1 in)	31
Wettest five days (Rx5day)	121.0 mm (4.8 in)	1964	45.8 mm (1.8 in)	31
Longest dry spell (CDD)	107 days	1969	52 days	31

Hottest day (TXx)

The hottest day of the year at Shelby AP, 1958 to 1988. The record is 41.1 C (106.0 F) in 1961, marked on the chart; the median year is 36.1 C (97.0 F).

Hottest day (TXx) at Shelby AP by year
Year	Hottest day (TXx)
1958	34.4 C (93.9 F)
1959	36.1 C (97.0 F)
1960	38.9 C (102.0 F)
1961	41.1 C (106.0 F)
1962	34.4 C (93.9 F)
1963	36.1 C (97.0 F)
1964	36.1 C (97.0 F)
1965	33.9 C (93.0 F)
1966	33.3 C (91.9 F)
1967	36.1 C (97.0 F)
1968	35.6 C (96.1 F)
1969	40.6 C (105.1 F)
1970	35.0 C (95.0 F)
1971	37.2 C (99.0 F)
1972	34.4 C (93.9 F)
1973	38.9 C (102.0 F)
1974	36.1 C (97.0 F)
1975	36.7 C (98.1 F)
1976	34.4 C (93.9 F)
1977	35.6 C (96.1 F)
1978	32.8 C (91.0 F)
1979	35.6 C (96.1 F)
1980	33.9 C (93.0 F)
1981	36.1 C (97.0 F)
1982	32.8 C (91.0 F)
1983	38.9 C (102.0 F)
1984	37.8 C (100.0 F)
1985	36.7 C (98.1 F)
1986	33.9 C (93.0 F)
1987	35.6 C (96.1 F)
1988	36.7 C (98.1 F)

Coldest night (TNn)

The coldest night of the year at Shelby AP, 1958 to 1988. The record is -41.7 C (-43.1 F) in 1983, marked on the chart; the median year is -33.3 C (-27.9 F).

Coldest night (TNn) at Shelby AP by year
Year	Coldest night (TNn)
1958	-28.9 C (-20.0 F)
1959	-33.3 C (-27.9 F)
1960	-33.9 C (-29.0 F)
1961	-32.8 C (-27.0 F)
1962	-31.7 C (-25.1 F)
1963	-33.3 C (-27.9 F)
1964	-34.4 C (-29.9 F)
1965	-30.6 C (-23.1 F)
1966	-31.1 C (-24.0 F)
1967	-31.1 C (-24.0 F)
1968	-40.0 C (-40.0 F)
1969	-37.2 C (-35.0 F)
1970	-31.7 C (-25.1 F)
1971	-35.0 C (-31.0 F)
1972	-38.3 C (-36.9 F)
1973	-29.4 C (-20.9 F)
1974	-35.0 C (-31.0 F)
1975	-30.6 C (-23.1 F)
1976	-31.7 C (-25.1 F)
1977	-36.1 C (-33.0 F)
1978	-32.8 C (-27.0 F)
1979	-36.7 C (-34.1 F)
1980	-33.9 C (-29.0 F)
1981	-32.8 C (-27.0 F)
1982	-34.4 C (-29.9 F)
1983	-41.7 C (-43.1 F)
1984	-33.9 C (-29.0 F)
1985	-33.9 C (-29.0 F)
1986	-32.8 C (-27.0 F)
1987	-25.6 C (-14.1 F)
1988	-27.8 C (-18.0 F)

Wettest day (Rx1day)

The wettest day of the year at Shelby AP, 1958 to 1988. The record is 68.6 mm (2.7 in) in 1964, marked on the chart; the median year is 28.2 mm (1.1 in).

Wettest day (Rx1day) at Shelby AP by year
Year	Wettest day (Rx1day)
1958	16.3 mm (0.6 in)
1959	28.2 mm (1.1 in)
1960	21.6 mm (0.9 in)
1961	19.3 mm (0.8 in)
1962	15.7 mm (0.6 in)
1963	20.8 mm (0.8 in)
1964	68.6 mm (2.7 in)
1965	59.4 mm (2.3 in)
1966	43.7 mm (1.7 in)
1967	26.2 mm (1.0 in)
1968	35.6 mm (1.4 in)
1969	43.7 mm (1.7 in)
1970	46.0 mm (1.8 in)
1971	14.0 mm (0.6 in)
1972	11.7 mm (0.5 in)
1973	33.3 mm (1.3 in)
1974	23.4 mm (0.9 in)
1975	51.1 mm (2.0 in)
1976	28.2 mm (1.1 in)
1977	20.3 mm (0.8 in)
1978	29.0 mm (1.1 in)
1979	15.7 mm (0.6 in)
1980	40.4 mm (1.6 in)
1981	65.5 mm (2.6 in)
1982	27.2 mm (1.1 in)
1983	16.0 mm (0.6 in)
1984	14.7 mm (0.6 in)
1985	42.2 mm (1.7 in)
1986	23.4 mm (0.9 in)
1987	36.6 mm (1.4 in)
1988	44.2 mm (1.7 in)

Wettest five days (Rx5day)

The wettest five days of the year at Shelby AP, 1958 to 1988. The record is 121.0 mm (4.8 in) in 1964, marked on the chart; the median year is 45.8 mm (1.8 in).

Wettest five days (Rx5day) at Shelby AP by year
Year	Wettest five days (Rx5day)
1958	20.1 mm (0.8 in)
1959	45.8 mm (1.8 in)
1960	35.8 mm (1.4 in)
1961	43.2 mm (1.7 in)
1962	20.5 mm (0.8 in)
1963	37.9 mm (1.5 in)
1964	121.0 mm (4.8 in)
1965	109.7 mm (4.3 in)
1966	59.7 mm (2.4 in)
1967	42.4 mm (1.7 in)
1968	52.3 mm (2.1 in)
1969	92.8 mm (3.7 in)
1970	52.9 mm (2.1 in)
1971	30.3 mm (1.2 in)
1972	25.2 mm (1.0 in)
1973	38.4 mm (1.5 in)
1974	47.3 mm (1.9 in)
1975	81.4 mm (3.2 in)
1976	52.8 mm (2.1 in)
1977	36.4 mm (1.4 in)
1978	52.6 mm (2.1 in)
1979	24.9 mm (1.0 in)
1980	57.7 mm (2.3 in)
1981	85.8 mm (3.4 in)
1982	43.2 mm (1.7 in)
1983	19.8 mm (0.8 in)
1984	17.7 mm (0.7 in)
1985	57.7 mm (2.3 in)
1986	33.8 mm (1.3 in)
1987	52.8 mm (2.1 in)
1988	47.5 mm (1.9 in)

Longest dry spell (CDD)

The longest dry spell of the year at Shelby AP, 1958 to 1988. The record is 107 days in 1969, marked on the chart; the median year is 52 days.

Longest dry spell (CDD) at Shelby AP by year
Year	Longest dry spell (CDD)
1958	20 days
1959	52 days
1960	93 days
1961	29 days
1962	41 days
1963	106 days
1964	64 days
1965	59 days
1966	35 days
1967	54 days
1968	66 days
1969	107 days
1970	40 days
1971	62 days
1972	34 days
1973	102 days
1974	57 days
1975	34 days
1976	52 days
1977	65 days
1978	50 days
1979	73 days
1980	31 days
1981	36 days
1982	62 days
1983	60 days
1984	38 days
1985	32 days
1986	32 days
1987	75 days
1988	35 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

28 years with a frost

Across 28 years with a frost, the median last spring frost at Shelby AP falls on 22 May and the median first autumn frost on 11 September, which leaves a median of 116 days between them.

Fitted over all years, the growing season changes by +3.5 days per decade at this station.

Frost dates and growing season at Shelby AP
Measure	Median, all years	Earliest period	Recent period (1959 to 1987)	Recent against earliest	Fitted trend
Last spring frost	22 May	n/a	22 May	n/a	-1.7 days per decade
First autumn frost	11 September	n/a	11 September	n/a	+1.8 days per decade
Growing days	116 days	n/a	116 days	n/a	+3.5 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.

Download the Data

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