Alpharetta 4 SSW Threshold Days by Year (USC00090219)

14 fixed thresholds counted per year at Alpharetta 4 SSW (USC00090219): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Alpharetta 4 SSW Thresholds

Alpharetta 4 SSW: days with 10 mm (0.39 in) or more of precipitation in 40 years, most in 1989 with 59.
Alpharetta 4 SSW: days with 25 mm (0.98 in) or more of precipitation in 40 years, most in 1989 with 26.
Alpharetta 4 SSW: days with 50 mm (1.97 in) or more of precipitation in 39 years, most in 1964 with 10.
Alpharetta 4 SSW: days with a maximum temperature at or above 30 C (86 F) in 37 years, most in 1962 with 108.
14 fixed thresholds have at least one qualifying day at Alpharetta 4 SSW.

Days at or above 30 C (86 F)

37 years with a qualifying day

Days per year at Alpharetta 4 SSW with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 108 in 1962.

Days at or above 30 C (86 F) per year at Alpharetta 4 SSW
Year	Days	Decade average
1902	93	85.5
1903	78	85.5
1958	81	86.5
1959	92	86.5
1960	81	70.7
1961	65	70.7
1962	108	70.7
1963	72	70.7
1964	83	70.7
1965	69	70.7
1966	59	70.7
1967	36	70.7
1968	66	70.7
1969	68	70.7
1970	90	61.2
1971	50	61.2
1972	48	61.2
1973	69	61.2
1975	54	61.2
1976	44	61.2
1977	85	61.2
1978	72	61.2
1979	39	61.2
1980	81	66.3
1982	34	66.3
1983	62	66.3
1984	45	66.3
1985	47	66.3
1986	92	66.3
1987	85	66.3
1988	76	66.3
1989	75	66.3
1991	44	37.5
1992	31	37.5
2008	61	57.5
2009	54	57.5
2010	94	94

For each year, a bar from the first to the last day at Alpharetta 4 SSW meeting 30 C (86 F).

First to last qualifying date each year at Alpharetta 4 SSW
Year	First date	Last date
1902	1902-04-25	1902-09-02
1903	1903-05-20	1903-09-13
1958	1958-04-24	1958-09-27
1959	1959-05-02	1959-10-05
1960	1960-04-24	1960-09-22
1961	1961-06-02	1961-09-28
1962	1962-05-01	1962-09-16
1963	1963-05-10	1963-09-22
1964	1964-04-21	1964-09-24
1965	1965-04-06	1965-09-21
1966	1966-06-09	1966-09-08
1967	1967-04-09	1967-09-21
1968	1968-05-25	1968-09-25
1969	1969-05-24	1969-09-19
1970	1970-04-24	1970-09-27
1971	1971-04-21	1971-10-02
1972	1972-04-16	1972-09-28
1973	1973-06-03	1973-09-25
1975	1975-05-22	1975-09-10
1976	1976-06-13	1976-09-10
1977	1977-04-17	1977-09-16
1978	1978-05-26	1978-09-23
1979	1979-06-03	1979-09-07
1980	1980-04-24	1980-09-25
1982	1982-05-29	1982-09-19
1983	1983-06-17	1983-09-13
1984	1984-05-29	1984-09-15
1985	1985-06-02	1985-09-12
1986	1986-04-27	1986-10-06
1987	1987-04-23	1987-09-15
1988	1988-04-06	1988-09-25
1989	1989-04-24	1989-09-15
1991	1991-05-19	1991-09-19
1992	1992-06-08	1992-09-09
2008	2008-06-01	2008-09-15
2009	2009-04-25	2009-08-27
2010	2010-04-06	2010-09-26

Every Fixed Threshold

Fixed thresholds at Alpharetta 4 SSW
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	37	108	1962	94
35 C (95 F): Days	21	21	1902	5
90 F (32.2 C): Days	37	64	1962	50
100 F (37.8 C): Days	5	3	1986	3
0 C (32 F): Ice days (max	35	11	2010	11
0 C (32 F): Frost days (min	37	125	1968	80
-10 C (14 F): Days with min	36	23	1977	7
-20 C (-4 F): Days with min	3	2	1963	1
20 C (68 F): Tropical nights (min	36	67	2010	67
10 mm (0.39 in): Days with 10 mm or more rain	40	59	1989	30
25 mm (0.98 in): Days with 25 mm or more rain	40	26	1989	10
50 mm (1.97 in): Days with 50 mm or more rain	39	10	1964	4
100 mm (3.94 in): Days with 100 mm or more rain	7	2	1961	1
10 cm (3.9 in): Days with 10 cm or more snowfall	2	1	1962	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1902.

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Data for Alpharetta 4 SSW 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). Threshold counts are computed by this site.

Data as of 2025-12-31. Last revised 31 December 2025 (2025-12-31).

Alpharetta 4 SSW Threshold Days by Year (USC00090219)

Key Facts for Alpharetta 4 SSW Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

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