Observed 4:00 PM EDT at KISP

Port Jefferson, NY weather

Sunny and 63°17°, jacket by 6 PM.

Forecasts agree

Now 63°17°

Sunny

Wind: 6 mph9 km/h; From the northwest. Up to 6 mph9 km/h through 4 AM
Dew point: 28°−2°; Dry · up to 37°3° by 5 PM (comfortable)
UV tomorrow: 4Moderate; Moderate 11 AM–4 PM · peak 4
Air today: 50Good; EPA forecast · PM2.5 (fine particles)
Pressure: 30.5 inHg1033 hPa; Falling slowly · −0.03 inHg−1.2 hPa in 3 h

No precipitation expected in the next 2 hours.

From forecast models

Next 48 hours

3°2° warmer than this time yesterday (59°15° then, 62°17° now)

Good hours for

Below 50°10° tonight after 8 PM
Low 41°5° tonight at 5 AM
Above 50°10° tomorrow by 10 AM

This afternoonNear 58°14° · Partly cloudy
TonightDown to 41°5° by 5 AM · Clear
Tomorrow morningUp to 54°12° by 11 AM · Clear
Tomorrow afternoonUp to 62°17° by 3 PM · Clear
Tomorrow nightDown to 46°8° by 3 AM · Clear
Monday morningUp to 56°13° by 11 AM · Clear
Monday afternoonUp to 64°18° by 2 PM · Clear

Hourly forecast, next 47 hours, in the place's local time
Hour	Conditions	Temperature	Feels like	Precipitation	Wind	Humidity	Cloud cover	UV index
Sat 4p	Partly sunny	58°14° (likely 56°13° to 59°15°)	58°14°	0%	3 mph5 km/h from W, gusts 9 mph14 km/h	45%	49%	1
Sat 5p	Sunny	57°14° (likely 55°13° to 58°14°)	57°14°	0%	3 mph5 km/h from W, gusts 9 mph14 km/h	47%	42%	0
Sat 6p	Partly cloudy	55°13° (likely 52°11° to 55°13°)	55°13°	0%	3 mph5 km/h from W, gusts 8 mph12 km/h	49%	34%	0
Sat 7p	Mostly clear	53°12° (likely 50°10° to 53°12°)	53°12°	0%	2 mph3 km/h from W, gusts 7 mph12 km/h	52%	61%	0
Sat 8p	Mostly clear	49°9° (likely 48°9° to 52°11°)	49°9°	0%	2 mph3 km/h from W, gusts 7 mph11 km/h	63%	53%	0
Sat 9p	Mostly clear	47°8° (likely 47°8° to 52°11°)	47°8°	0%	2 mph3 km/h from W, gusts 6 mph10 km/h	68%	42%	0
Sat 10p	Mostly clear	47°8° (likely 46°8° to 51°11°)	47°8°	0%	1 mph2 km/h from W, gusts 7 mph11 km/h	68%	41%	0
Sat 11p	Clear	46°8° (likely 45°7° to 50°10°)	46°8°	0%	1 mph2 km/h from W, gusts 6 mph9 km/h	73%	19%	0
Sun 12a	Clear	45°7° (likely 44°7° to 49°9°)	45°7°	0%	1 mph2 km/h from NW, gusts 7 mph11 km/h	76%	2%	0
Sun 1a	Clear	45°7° (likely 43°6° to 48°9°)	45°7°	0%	2 mph3 km/h from NW, gusts 7 mph11 km/h	76%	0%	0
Sun 2a	Clear	44°7° (likely 43°6° to 48°9°)	44°7°	0%	2 mph3 km/h from NW, gusts 8 mph12 km/h	79%	0%	0
Sun 3a	Clear	43°6° (likely 42°6° to 49°9°)	43°6°	0%	2 mph3 km/h from NW, gusts 7 mph11 km/h	82%	0%	0
Sun 4a	Clear	43°6° (likely 42°6° to 48°9°)	43°6°	0%	2 mph3 km/h from N, gusts 7 mph11 km/h	82%	0%	0
Sun 5a	Clear	41°5° (likely 41°5° to 48°9°)	41°5°	0%	2 mph3 km/h from N, gusts 7 mph11 km/h	89%	0%	0
Sun 6a	Clear	42°6° (likely 41°5° to 47°8°)	42°6°	0%	2 mph3 km/h from N, gusts 6 mph10 km/h	86%	0%	0
Sun 7a	Sunny	42°6° (likely 41°5° to 46°8°)	40°4°	0%	3 mph5 km/h from N, gusts 5 mph9 km/h	86%	0%	0
Sun 8a	Sunny	43°6° (likely 42°6° to 46°8°)	41°5°	0%	3 mph5 km/h from N, gusts 5 mph9 km/h	86%	0%	0
Sun 9a	Sunny	48°9° (likely 47°8° to 50°10°)	47°8°	0%	3 mph5 km/h from N, gusts 4 mph7 km/h	71%	0%	1
Sun 10a	Sunny	51°11° (likely 51°11° to 54°12°)	51°11°	0%	3 mph5 km/h from N, gusts 5 mph9 km/h	63%	0%	2
Sun 11a	Sunny	54°12° (likely 54°12° to 57°14°)	54°12°	0%	3 mph5 km/h from N, gusts 6 mph9 km/h	59%	0%	3
Sun 12p	Sunny	57°14° (likely 57°14° to 60°16°)	57°14°	0%	3 mph5 km/h from N, gusts 8 mph12 km/h	51%	0%	4
Sun 1p	Sunny	60°16° (likely 59°15° to 62°17°)	60°16°	0%	3 mph5 km/h from NW, gusts 7 mph11 km/h	46%	0%	4
Sun 2p	Sunny	61°16° (likely 60°16° to 63°17°)	61°16°	0%	3 mph5 km/h from NW, gusts 7 mph11 km/h	44%	0%	4
Sun 3p	Sunny	62°17° (likely 61°16° to 64°18°)	62°17°	0%	3 mph5 km/h from W, gusts 6 mph9 km/h	43%	0%	3
Sun 4p	Sunny	62°17° (likely 60°16° to 64°18°)	62°17°	0%	3 mph5 km/h from W, gusts 6 mph10 km/h	43%	0%	2
Sun 5p	Sunny	61°16° (likely 59°15° to 62°17°)	61°16°	0%	3 mph5 km/h from SW, gusts 5 mph8 km/h	44%	0%	1
Sun 6p	Clear	59°15° (likely 55°13° to 59°15°)	59°15°	0%	3 mph5 km/h from SW, gusts 7 mph12 km/h	49%	0%	0
Sun 7p	Clear	56°13° (likely 51°11° to 56°13°)	56°13°	0%	3 mph5 km/h from SW, gusts 10 mph15 km/h	57%	0%	0
Sun 8p	Clear	50°10° (likely 49°9° to 53°12°)	49°9°	0%	3 mph5 km/h from S, gusts 11 mph17 km/h	74%	0%	0
Sun 9p	Clear	50°10° (likely 48°9° to 53°12°)	49°9°	0%	3 mph5 km/h from SW, gusts 12 mph19 km/h	74%	0%	0
Sun 10p	Clear	49°9° (likely 47°8° to 53°12°)	48°9°	0%	3 mph5 km/h from SW, gusts 12 mph19 km/h	80%	0%	0
Sun 11p	Clear	49°9° (likely 47°8° to 52°11°)	48°9°	0%	3 mph5 km/h from SW, gusts 11 mph18 km/h	83%	0%	0
Mon 12a	Clear	48°9° (likely 46°8° to 52°11°)	47°8°	0%	3 mph5 km/h from SW, gusts 12 mph19 km/h	83%	0%	0
Mon 1a	Clear	48°9° (likely 45°7° to 51°11°)	46°8°	0%	5 mph8 km/h from W, gusts 11 mph18 km/h	83%	0%	0
Mon 2a	Clear	48°9° (likely 45°7° to 50°10°)	46°8°	0%	5 mph8 km/h from W, gusts 12 mph19 km/h	83%	0%	0
Mon 3a	Clear	46°8° (likely 45°7° to 50°10°)	44°7°	0%	5 mph8 km/h from W, gusts 12 mph19 km/h	89%	0%	0
Mon 4a	Clear	46°8° (likely 44°7° to 49°9°)	44°7°	0%	5 mph8 km/h from W, gusts 11 mph18 km/h	89%	0%	0
Mon 5a	Clear	46°8° (likely 44°7° to 49°9°)	44°7°	0%	5 mph8 km/h from W, gusts 14 mph23 km/h	93%	0%	0
Mon 6a	Clear	45°7° (likely 44°7° to 49°9°)	43°6°	0%	5 mph8 km/h from W, gusts 13 mph21 km/h	93%	1%	0
Mon 7a	Sunny	45°7° (likely 43°6° to 48°9°)	42°6°	0%	6 mph10 km/h from W, gusts 13 mph21 km/h	93%	11%	0
Mon 8a	Sunny	46°8° (likely 44°7° to 49°9°)	43°6°	0%	6 mph10 km/h from W, gusts 13 mph21 km/h	89%	8%	0
Mon 9a	Sunny	50°10° (likely 49°9° to 53°12°)	48°9°	0%	6 mph10 km/h from W, gusts 13 mph22 km/h	77%	9%	1
Mon 10a	Sunny	53°12° (likely 53°12° to 57°14°)	53°12°	0%	7 mph11 km/h from W, gusts 13 mph21 km/h	71%	10%	2
Mon 11a	Sunny	56°13° (likely 55°13° to 60°16°)	56°13°	0%	7 mph11 km/h from W, gusts 13 mph20 km/h	66%	9%	3
Mon 12p	Sunny	59°15° (likely 57°14° to 61°16°)	59°15°	0%	7 mph11 km/h from W, gusts 12 mph19 km/h	62%	2%	4
Mon 1p	Sunny	62°17° (likely 59°15° to 63°17°)	62°17°	0%	8 mph13 km/h from W, gusts 12 mph19 km/h	56%	2%	4
Mon 2p	Sunny	64°18° (likely 61°16° to 65°18°)	64°18°	0%	8 mph13 km/h from W, gusts 12 mph19 km/h	54%	0%	4

Days ahead

Shaded: typical range for these dates (1991–2020)

Today, Oct 24. Cloudy. High 58°14°, low 41°5°. Typical 61°16° / 44°7°. Dry. Forecasts agree.
1. Afternoon
  noon–6 PM
  Sunny, 58°14°
  Dry
2. Evening
  6 PM–midnight
  Mostly clear, 49°9°
  Dry
3. Overnight
  midnight–6 AM
  Clear, 41°5°
  Dry
Official NWS forecast
Today: Mostly sunny, with a high near 58. West wind around 5 mph.
Tonight: Mostly clear, with a low around 41. Northwest wind around 3 mph.
Forecasts agreeIndependent forecasts are close; the range is narrow.
High, likely
56°13°–59°15°
Low, likely
39°4°–44°7°
Typical high / low
61°16° / 44°7°
Wind
10 mph17 km/h
UV peak
4
Tomorrow, Oct 25. Sunny. High 62°17°, low 45°7°. Typical 61°16° / 44°7°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Sunny, 43°6°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 62°17°
  Dry
3. Evening
  6 PM–midnight
  Clear, 50°10°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 46°8°
  Dry
Official NWS forecast
Day: Sunny, with a high near 62. Northwest wind around 3 mph.
Night: Clear, with a low around 45. Southwest wind around 5 mph.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
61°16°–64°18°
Low, likely
41°5°–46°8°
Typical high / low
61°16° / 44°7°
Wind
8 mph13 km/h, gusts 17 mph27 km/h
UV peak
4
Monday, Oct 26. Sunny. High 66°19°, low 49°9°. Typical 61°16° / 44°7°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Sunny, 46°8°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 64°18°
  Dry
3. Evening
  6 PM–midnight
  Clear, 58°14°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 53°12°
  Dry
Official NWS forecast
Day: Sunny, with a high near 66. West wind 5 to 8 mph.
Night: Clear. Low around 49, with temperatures rising to around 51 overnight.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
62°17°–66°19°
Low, likely
43°6°–49°9°
Typical high / low
61°16° / 44°7°
Wind
9 mph15 km/h, gusts 21 mph34 km/h
UV peak
4
Tuesday, Oct 27. Sunny. High 58°14°, low 43°6°. Typical 60°16° / 43°6°. Dry. Forecasts agree.
1. Morning
  6 AM–noon
  Sunny, 50°10°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 54°12°
  Dry
3. Evening
  6 PM–midnight
  Clear, 49°10°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 44°6°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 58.
Night: Mostly clear, with a low around 43.
Forecasts agreeIndependent forecasts are close; the range is narrow.
High, likely
57°14°–59°15°
Low, likely
42°6°–51°11°
Typical high / low
60°16° / 43°6°
Wind
15 mph24 km/h, gusts 24 mph39 km/h
UV peak
4
Wednesday, Oct 28. Mostly sunny. High 56°13°, low 47°8°. Typical 60°16° / 43°6°. Dry. Forecasts differ.
1. Morning
  6 AM–noon
  Sunny, 44°7°
  Dry
2. Afternoon
  noon–6 PM
  Mostly sunny, 56°13°
  Dry
3. Evening
  6 PM–midnight
  Cloudy, 50°10°
  Dry
4. Overnight
  midnight–6 AM
  Cloudy, 50°10°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 56.
Night: Partly cloudy, with a low around 47.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
High, likely
53°12°–58°14°
Low, likely
39°4°–47°8°
Typical high / low
60°16° / 43°6°
Wind
13 mph21 km/h
UV peak
4
Thursday, Oct 29. Partly sunny. High 63°17°, low 53°12°. Typical 60°16° / 43°6°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Sunny, 51°10°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 62°17°
  Dry
3. Evening
  6 PM–midnight
  Clear, 56°14°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 54°12°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Mostly sunny, with a high near 63.
Night: Mostly clear, with a low around 53.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
60°16°–64°18°
Low, likely
46°8°–53°12°
Typical high / low
60°16° / 43°6°
Wind
13 mph21 km/h, gusts 22 mph36 km/h
UV peak
4
Friday, Oct 30. Mostly sunny. High 67°19°, low 52°11°. Typical 59°15° / 42°6°. Dry. Forecasts differ.
1. Morning
  6 AM–noon
  Sunny, 53°12°
  Dry
2. Afternoon
  noon–6 PM
  Sunny, 67°19°
  Dry
3. Evening
  6 PM–midnight
  Clear, 59°15°
  Dry
4. Overnight
  midnight–6 AM
  Clear, 54°12°
  Dry
Hours this far out come from computer models only.
Official NWS forecast
Day: Sunny, with a high near 67.
Night: Mostly clear, with a low around 52.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
High, likely
64°18°–69°21°
Low, likely
50°10°–54°12°
Typical high / low
59°15° / 42°6°
Wind
12 mph19 km/h, gusts 25 mph41 km/h
UV peak
4
Saturday, Oct 31. Cloudy. High 63°17°, low 52°11°. Typical 59°15° / 42°6°. Dry. Mostly agree.
1. Morning
  6 AM–noon
  Sunny, 53°12°
  Dry
2. Afternoon
  noon–6 PM
  Mostly sunny, 65°18°
  Dry
3. Evening
  6 PM–midnight
  Cloudy, 56°14°
  Dry
4. Overnight
  midnight–6 AM
  Cloudy, 56°13°
  Dry
Hours this far out come from computer models only.
The National Weather Service writes about seven days ahead; this day is our model forecast only.
Mostly agreeIndependent forecasts are fairly close; small surprises are possible.
High, likely
60°16°–67°19°
Low, likely
49°9°–55°13°
Typical high / low
59°15° / 42°6°
Wind
12 mph20 km/h, gusts 24 mph38 km/h
UV peak
4
Sunday, Nov 1. Drizzle. High 63°17°, low 55°13°. Typical 58°14° / 42°6°. Rain 0.02 in0.5 mm, 30% chance. Forecasts differ.
1. Morning
  6 AM–noon
  Cloudy, 58°15°
  Dry
2. Afternoon
  noon–6 PM
  Cloudy, 62°17°
  Dry
3. Evening
  6 PM–midnight
  Cloudy, 60°16°
  30% chance · 0.01 in0.4 mm
4. Overnight
  midnight–6 AM
  Drizzle, 60°16°
  30% chance · 0.04 in1.1 mm
Hours this far out come from computer models only.
The National Weather Service writes about seven days ahead; this day is our model forecast only.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
High, likely
57°14°–69°21°
Low, likely
53°12°–59°15°
Typical high / low
58°14° / 42°6°
Wind
12 mph19 km/h, gusts 23 mph37 km/h
UV peak
2
Monday, Nov 2. Cloudy. High 65°18°, low 59°15°. Typical 58°14° / 42°6°. Rain 0.74 in19 mm, 30% chance. Forecasts differ.
1. Morning
  6 AM–noon
  Showers, 62°16°
  30% chance · 0.25 in6.2 mm
2. Afternoon
  noon–6 PM
  Showers, 65°18°
  20% chance · 0.27 in6.8 mm
3. Evening
  6 PM–midnight
  Showers, 64°18°
  Dry
Hours this far out come from computer models only.
The National Weather Service writes about seven days ahead; this day is our model forecast only.
Forecasts differIndependent forecasts disagree; expect changes and plan for the range.
High, likely
61°16°–69°21°
Low, likely
56°13°–64°18°
Typical high / low
58°14° / 42°6°
Wind
23 mph36 km/h, gusts 39 mph63 km/h

10 days15 days30 days

The outlook

Today
Dry, high 58°, low 41°.
Tomorrow
Dry, high 62°, low 45°, warming up.
Monday
Dry, high 66°, low 49°, warming up.
Rest of week
Mostly dry, highs 56–67°.

Want the meteorologists’ reasoning? Read the NWS forecast discussion (OKX) (opens in a new tab)

What changed since yesterday

No meaningful changes from yesterday’s forecast.

Radar

Radar data: NOAA MRMS, rendered by forecast.blue

Radar loads when scrolled into view

Full-screen radar

Rivers

NOAA river gauges within 25 mi

Long Island Sound near Bridgeport Harbor (IN MLLW)

18 mi

Below flood stage

Level: 2.0 ft

Forecast peak 9.1 ft Tue 12 PM, minor flooding

Reading from Sat 3:06 PM · NWS gauge page

Flax Pond at Old Field (IN MLLW)

4.9 mi

Below flood stage

Level: 5.3 ft

Reading from Sat 2:24 PM · NWS gauge page

Great South Bay at Watch Hill (IN MLLW)

18 mi

Below flood stage

Level: 1.5 ft

Reading from Sat 3 PM · NWS gauge page

Moriches Bay at Moriches Bay (IN MLLW)

19 mi

Below flood stage

Level: 1.5 ft

Reading from Sat 2:48 PM · NWS gauge page

For your home

What this week’s weather means for heating, cooling, pipes and fresh air.

Heating this week

About 70% less heating than a typical week.

This week 27Typical 93

Heating degree days, base 65°F

Heat-pump hours, next 7 days

h below 47°F: 18
h below 17°F: 0
h below 5°F: 0

47, 17 and 5°F are the test points heat pumps are rated at. About 3 hours are near freezing and damp, when outdoor units defrost more often.

Comfort

Dry air outside (dew point 28°F).

Open the windows?

Sun, 1:00 PM–5:00 PM

Good stretch to open the windows.

Is this typical?

Islip-Li Macarthur Airport · official normals 1991–2020 · records 1963–2026

Oct 24, today vs a typical year

Today’s expected high is 3°2° colder than typical.

Last 7 days vs normal

On average 1° colder than normal (daily mean temperature).

−6°−3°SunOct 18
−4°−2°MonOct 19
+3°+1°TueOct 20
+2°+1°WedOct 21
+4°+2°ThuOct 22
−4°−2°FriOct 23
—SatOct 24

Port Jefferson weather by month: normals, records, snow and freeze dates

Sun & moon

Sun

Daylight: 10 h 45 min; Losing 2 min 35 s a day; shortest Dec 21, 1 h 31 min less
Golden hour: 5:20–6:15 PM; Morning 6:56–7:51 AM
Blue hour: 6:15–6:26 PM; Morning 6:45–6:56 AM; first light 6:45 AM

Stars tonight? Fair

Mostly clear 11 PM–6:46 AM, but the moon is 99% lit and up.

Moon

Waxing gibbous

98% lit · growing

Today: sets 5:24 AM · rises 4:55 PM
Full moon: Oct 26
New moon: Nov 9

Looking north from Port Jefferson. The highest point on the skyline is about 7,600 ft, 76 mi away.Skyline from USGS elevation data, heights drawn up to 6× taller. Sky, sun and moon as they are now.

Port Jefferson, NY weather

Next 2 hours

Next 48 hours

Days ahead

The outlook

Today

Tomorrow

Monday

Rest of week

What changed since yesterday

Radar

Rivers

Long Island Sound near Bridgeport Harbor (IN MLLW)

Flax Pond at Old Field (IN MLLW)

Great South Bay at Watch Hill (IN MLLW)

Moriches Bay at Moriches Bay (IN MLLW)

For your home

Heating this week

Heat-pump hours, next 7 days

Comfort

Open the windows?

Is this typical?

Oct 24, today vs a typical year

Last 7 days vs normal

Sun & moon

Sun

Stars tonight? Fair

Moon