Weather in Port Jefferson, NY
Port Jefferson, Sunday, 9 August, 08:23
Partly cloudy. Feels like 79°. High 90°, low 73°.
Monthly outlook for Port Jefferson, NY: average high 80.9°, average low 70.8°. That is 1.2° above the climate normal for August. Precipitation is expected on 5 days (about 0.6 inches), against a normal of 5 days and 2.2 inches. The warmest day looks like 9 August (89.6°), the coolest 15 August (63°).
Ten-day blocks vs climate normal
| Period | Forecast high | Normal | Difference |
|---|---|---|---|
| 9 August – 18 August | 80.4° | 79.6° | +0.5° |
| 19 August – 28 August | 81.7° | 77.9° | +2.1° |
| 29 August – 7 September | at normal | 76.4° | — |
August records over 66 years
Climate normals and records are computed from the nearest reference point — Stony Brook University (4 mi).
0Port Jefferson, Monday, 10 August
Partly cloudy. High 87°, low 71°.
0.07
Port Jefferson, Tuesday, 11 August
Rain. High 84°, low 74°.
0
Port Jefferson, Wednesday, 12 August
Overcast. High 77°, low 73°.
0.09Port Jefferson, Thursday, 13 August
Light rain. High 80°, low 70°.
0
Port Jefferson, Friday, 14 August
Clear. High 75°, low 64°.
0Port Jefferson, Saturday, 15 August
Clear. High 77°, low 63°.
0Port Jefferson, Sunday, 16 August
Overcast. High 78°, low 67°.
0Port Jefferson, Monday, 17 August
Partly cloudy. High 78°, low 69°.
0.04Port Jefferson, Tuesday, 18 August
Light rain. High 79°, low 69°.
0.02Port Jefferson, Wednesday, 19 August
Light rain. High 80°, low 72°.
0Port Jefferson, Thursday, 20 August
Clear. High 82°, low 71°.
0.11Port Jefferson, Friday, 21 August
Light rain. High 83°, low 74°.
0.07Port Jefferson, Saturday, 22 August
Light rain. High 85°, low 75°.
0Port Jefferson, Sunday, 23 August
Clear. High 82°, low 74°.
0.15Port Jefferson, Monday, 24 August
Light rain. High 80°, low 75°.
0.09Port Jefferson, Tuesday, 25 August
Climate normal for this date — 60-year average.
0.09Port Jefferson, Wednesday, 26 August
Climate normal for this date — 60-year average.
0.11Port Jefferson, Thursday, 27 August
Climate normal for this date — 60-year average.
0.18
Port Jefferson, Friday, 28 August
Climate normal for this date — 60-year average.
0.16Port Jefferson, Saturday, 29 August
Climate normal for this date — 60-year average.
0.08Port Jefferson, Sunday, 30 August
Climate normal for this date — 60-year average.
0.05
Port Jefferson, Monday, 31 August
Climate normal for this date — 60-year average.
0.07Port Jefferson, Tuesday, 1 September
Climate normal for this date — 60-year average.
0.19Port Jefferson, Wednesday, 2 September
Climate normal for this date — 60-year average.
0.11Port Jefferson, Thursday, 3 September
Climate normal for this date — 60-year average.
0.12Port Jefferson, Friday, 4 September
Climate normal for this date — 60-year average.
0.05Port Jefferson, Saturday, 5 September
Climate normal for this date — 60-year average.
0.14Port Jefferson, Sunday, 6 September
Climate normal for this date — 60-year average.
0.1Port Jefferson, Monday, 7 September
Climate normal for this date — 60-year average.
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Port Jefferson, NY are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Port Jefferson, NY since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.
Sun and moon today
Weather history
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