40.794°N, 73.102°W · station ISPthr · 64 years of record
60°F
COLDEST SEP 6 SINCE 2024
forecast low · Sep 6
7-Day Forecast
NWS NDFD forecast low temperature for Islip.
This Day in History
Every year's low on each of the next 7 forecast dates at Islip — toggle a day below. The forecast line shows where it lands; the ringed bar is the coldest on record.
Ranks
#45 / 62
coldest Sep 2 in 62 yrs of record
Coldest Sep 2 ever
49°F
set in 1991
Mildest Sep 2 ever
75°F
set in 1980
Forecast low 65°F — 45th coldest Sep 2 of 62 years · record 49°F (1991) · coldest since 2025.
Ranks
#43 / 62
coldest Sep 3 in 62 yrs of record
Coldest Sep 3 ever
47°F
set in 1992
Mildest Sep 3 ever
74°F
set in 1993
Forecast low 65°F — 43rd coldest Sep 3 of 62 years · record 47°F (1992) · coldest since 2025.
Ranks
#49 / 62
coldest Sep 4 in 62 yrs of record
Coldest Sep 4 ever
49°F
set in 1975
Mildest Sep 4 ever
74°F
set in 2018
Forecast low 68°F — 49th coldest Sep 4 of 62 years · record 49°F (1975) · coldest since 2025.
Ranks
#39 / 63
coldest Sep 5 in 63 yrs of record
Coldest Sep 5 ever
49°F
set in 1989
Mildest Sep 5 ever
74°F
set in 1985
Forecast low 64°F — 39th coldest Sep 5 of 63 years · record 49°F (1989) · coldest since 2024.
Ranks
#28 / 63
coldest Sep 6 in 63 yrs of record
Coldest Sep 6 ever
49°F
set in 1965
Mildest Sep 6 ever
75°F
set in 1985
Forecast low 60°F — 28th coldest Sep 6 of 63 years · record 49°F (1965) · coldest since 2024.
Ranks
#30 / 63
coldest Sep 7 in 63 yrs of record
Coldest Sep 7 ever
49°F
set in 1988
Mildest Sep 7 ever
73°F
set in 1999
Forecast low 60°F — 30th coldest Sep 7 of 63 years · record 49°F (1988) · coldest since 2025.
Ranks
#36 / 63
coldest Sep 8 in 63 yrs of record
Coldest Sep 8 ever
46°F
set in 1988
Mildest Sep 8 ever
77°F
set in 2023
Forecast low 62°F — 36th coldest Sep 8 of 63 years · record 46°F (1988) · coldest since 2025.
The hottest and coldest ever recorded at Islip in each calendar month, and for the whole 1963–2026 record — with the year each was set.
Month
Record High
Record Low
Jan
69°FJan 29, 2002
-8°FJan 18, 1965
Feb
71°FFeb 16, 2023
-14°FFeb 13, 1967
Mar
82°FMar 13, 1990
0°FMar 18, 1967
Apr
94°FApr 17, 2002
16°FApr 1, 1969
May
98°FMay 20, 1996
32°FMay 1, 2008
Jun
101°FJun 24, 2025
42°FJun 1, 1967
Jul
104°FJul 3, 1966
49°FJul 2, 1965
Aug
100°FAug 2, 1975
45°FAug 31, 1965
Sep
94°FSep 3, 1973
38°FSep 24, 1963
Oct
89°FOct 2, 2019
23°FOct 31, 1966
Nov
80°FNov 7, 2022
11°FNov 24, 1989
Dec
77°FDec 7, 1998
-1°FDec 31, 1963
All-time
104°FJul 3, 1966
-14°FFeb 13, 1967
2026 Records So Far
Records set or tied at Islip so far this year — through Aug 30.
Record Highs in 2026
3 broke
plus 2 tied — daily record highs set this year
Record Lows in 2026
1 broke
plus 0 tied — daily record lows set this year
Record Warm Nights & Cold Days
Two more daily records, kept separate from the rankings: the warmest a night has ever stayed (record high minimum) and the coldest a day has ever gotten (record low maximum) — the flip side of the usual record high and low.
Warmest low ever
81°F
record high minimum — the night it never cooled · Jul 6, 1999
Coldest high ever
6°F
record low maximum — the day it never warmed · Jan 21, 1985
Month
Warmest low
Coldest high
Jan
55°FJan 15, 1995
6°FJan 21, 1985
Feb
47°FFeb 20, 1981
10°FFeb 17, 1979
Mar
55°FMar 28, 1998
18°FMar 18, 1967
Apr
62°FApr 18, 2002
32°FApr 7, 1982
May
70°FMay 28, 1991
44°FMay 7, 1967
Jun
77°FJun 21, 2012
53°FJun 2, 2015
Jul
81°FJul 6, 1999
61°FJul 4, 1978
Aug
80°FAug 2, 2006
60°FAug 21, 2007
Sep
77°FSep 8, 2023
54°FSep 30, 2001
Oct
72°FOct 8, 2005
40°FOct 27, 1976
Nov
65°FNov 2, 1971
29°FNov 23, 1989
Dec
55°FDec 24, 2015
11°FDec 25, 1983
All-time
81°FJul 6, 1999
6°FJan 21, 1985
Cold Streaks
Current run
0 days
consecutive days with a low ≤ 32°F
Longest ever
68 days
record run, ended Mar 9 1978
So far in 2026
67 days
days with a low ≤ 32°F this year
Climate Normals
Normal low & low by month, from Islip's own 1991–2020 record. Today's normal low: 62°F · forecast is -2° vs normal.