Wellesley Island Threshold Days by Year (USC00309055)

15 fixed thresholds counted per year at Wellesley Island (USC00309055): hot days, frost, tropical nights and heavy rain, with the most days in a year.

Key Facts for Wellesley Island Thresholds

Wellesley Island: days with 10 mm (0.39 in) or more of precipitation in 28 years, most in 1976 with 39.
Wellesley Island: days with 25 mm (0.98 in) or more of precipitation in 28 years, most in 1977 with 9.
Wellesley Island: days with 10 cm (3.9 in) or more of snowfall in 27 years, most in 1977 with 12.
Wellesley Island: nights with a minimum temperature at or below 0 C (32 F) in 20 years, most in 1978 with 182.
15 fixed thresholds have at least one qualifying day at Wellesley Island.

Days at or above 30 C (86 F)

17 years with a qualifying day

Days per year at Wellesley Island with a maximum temperature at or above 30 C (86 F), with the decade average as a line. The most was 44 in 1983.

Days at or above 30 C (86 F) per year at Wellesley Island
Year	Days	Decade average
1975	21	17.2
1976	4	17.2
1977	14	17.2
1978	28	17.2
1979	19	17.2
1980	7	18.7
1981	13	18.7
1982	11	18.7
1983	44	18.7
1984	17	18.7
1985	13	18.7
1986	5	18.7
1987	23	18.7
1988	37	18.7
1989	17	18.7
1990	10	11
1993	12	11

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

First to last qualifying date each year at Wellesley Island
Year	First date	Last date
1975	1975-07-03	1975-08-18
1976	1976-07-19	1976-08-24
1977	1977-06-28	1977-08-29
1978	1978-06-12	1978-08-20
1979	1979-06-10	1979-09-01
1980	1980-07-19	1980-08-25
1981	1981-07-02	1981-08-06
1982	1982-07-07	1982-07-26
1983	1983-06-14	1983-09-21
1984	1984-06-08	1984-08-08
1985	1985-07-05	1985-08-18
1986	1986-07-20	1986-07-29
1987	1987-06-25	1987-08-18
1988	1988-06-14	1988-08-16
1989	1989-06-24	1989-08-15
1990	1990-04-28	1990-08-10
1993	1993-06-24	1993-08-27

Every Fixed Threshold

Fixed thresholds at Wellesley Island
Threshold	Years with a qualifying day	Most days in a year	Year	Latest year days
30 C (86 F): Days	17	44	1983	12
35 C (95 F): Days	1	3	1988	3
90 F (32.2 C): Days	12	19	1988	1
0 C (32 F): Ice days (max	18	81	1978	57
0 C (32 F): Frost days (min	20	182	1978	149
-10 C (14 F): Days with min	20	80	1978	58
-20 C (-4 F): Days with min	20	29	1976	17
-30 C (-22 F): Days with min	12	8	1979	3
20 C (68 F): Tropical nights (min	19	9	1983	4
10 mm (0.39 in): Days with 10 mm or more rain	28	39	1976	34
25 mm (0.98 in): Days with 25 mm or more rain	28	9	1977	7
50 mm (1.97 in): Days with 50 mm or more rain	15	2	1975	1
100 mm (3.94 in): Days with 100 mm or more rain	1	1	1979	1
10 cm (3.9 in): Days with 10 cm or more snowfall	27	12	1977	1
25 cm (9.8 in): Days with 25 cm or more snowfall	9	4	1977	1

Years with under 90 percent of days observed are left out of the most days column. Threshold history at this station starts in 1975.

Download the Data

Data for Wellesley Island 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).

Wellesley Island Threshold Days by Year (USC00309055)

Key Facts for Wellesley Island Thresholds

Days at or above 30 C (86 F)

Every Fixed Threshold

Download the Data

Related