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Forecast Discussion for New York City/Upton, NY

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330
FXUS61 KOKX 300759
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
359 AM EDT Tue Jun 30 2026

.WHAT HAS CHANGED...
An Extreme Heat Warning is now in effect for NYC, northeast NJ, the
Lower Hudson Valley and much of southern CT for Wednesday. Long
Island and southeastern parts of CT remain in an Extreme Heat Watch
for Wednesday given a downward trend in forecast temperatures.

The Extreme Heat Watch from Thursday through Saturday remains
unchanged for the entire area.

&&

.KEY MESSAGES...
1) Near record, dangerous heat is expected to start Wednesday
for most, peak Thursday through Friday and potentially linger
into Saturday, with little overnight relief. This level of heat
can be deadly for those without adequate cooling and hydration.
Impacts to transportation infrastructure and electrical and
water systems are also possible.

2) Slight chance for afternoon/evening thunderstorms today.
Isolated to scattered strong to severe thunderstorms are
possible each day Wednesday through Saturday, particularly in
the afternoon/evening.

3) There is a high risk of rip currents on Wednesday (see marine
section for discussion)

&&

.DISCUSSION...
.KEY MESSAGE 1...
Guidance continues to be in great agreement in anomalously
strong ridging centered over the Tennessee/Ohio Valley for mid
to late week. The ridging gradually gets suppressed through the
weekend as northern stream closed low develops and slides
through SE Canada. At the surface, high pressure strengthens
over the area early today then shifts offshore. The high remains
offshore through the week as a surface trough lingers over the
area. This set up will bring a prolonged period of dangerous
heat and humidity to the area.

Confidence was high enough to upgrade NYC, northeast NJ, the
Lower Hudson Valley and much of southern CT to an Extreme Heat
Warning for Wednesday. The Extreme Heat Watch was left for now
for Long Island and portions of southeastern CT for Wednesday
where forecast temperatures and Heat Index values have lowered.
One factor contributing to this has been the upward trend in the
S/SW flow off the water. 850mb temperatures have also lowered a
few degrees, closer to 20-22C. While conditions will still be
hot and humid in these areas on Wednesday, it is unclear if
conditions will meet Warning criteria.

The heat and humidity will likely peak Thursday and Friday.
During this period, guidance shows 500mb heights peaking around
592-595dam, and 850mb temps peaking around 24-25C. Both of these
are above the 90th percentile of observed values by the OKX
RAOB, with 1956 being the last time an 850 temp over 24C was
observed! NBM dewpoint spread has also lowered a bit since 24
hours ago and appears to be converging on values in the lower
to mid 70s. Uncertainty then increases for Saturday with large
spread in dewpoints seen and more widespread showers/thunderstorms
expected.

Just as importantly as the high temps will be lack of overnight
relief as lows Wed night thru Fri Night are not likely to
drop below the lower 80s for the NYC/NJ urban centers, and
upper 70s for much of the rest of the area.

This level of heat can be deadly for those without adequate
cooling and hydration. Impacts to transportation (rail, bridge,
road/tarmac) infrastructure and electrical (high demand
electrical) and water systems (open hydrants reducing water
pressure) have been noted with previous heat events of this
severity and duration.

.KEY MESSAGE 2...
Given our placement on the northern periphery of the upper
level ridge, we are set up for potential convection/MCSs
rounding the periphery of the ridge. While this is common in
this pattern, there is inherent uncertainty in timing, placement
and strength of this activity.

CAMs continue to show decaying convection approach from the
northwest later this afternoon into the evening. The SPC
continue to keep the marginal and slight risk to our northwest.
This is as expected as any convection will be entering a less
favorable environment.

The story for Wednesday remains the same. While MLCAPE values
could reach 2000-3000 J/kg, there is uncertainty in a trigger
and weak shear. CAMs show some isolated to scattered activity
and the SPC has kept a marginal risk to our north and west.

Uncertainty increase thereafter, with greater coverage in
showers/thunderstorms Friday into the weekend.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
High pressure remains over the Western Atlantic through the TAF
period. A warm front passes northeast of the area late today into
this evening.

Mainly VFR conditions are expected through the TAF period.
Exceptions would be near KGON where some low stratus and fog are
forecast to develop overnight into early morning with associated
brief MVFR to IFR as well as KSWF where there could be scattered
shower activity this afternoon. Shower activity is more uncertain
with most places only having a slight chance so left out any MVFR or
less conditions with those. There is also a slight chance of
thunderstorms.

Regarding winds into early morning, a few locations have variable
direction with light winds speeds of near 5 kts or less but overall
a general S-SW wind is expected during the TAF period. Wind speeds
increase to near 10-15 kt today into early this evening with KJFK
relatively higher for this afternoon into early evening. For the
afternoon into evening, gusts to near 20-25 kt are forecast for most
terminals. Winds and gusts decrease by mid to late this evening.

...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

For tonight, slight chance of a shower or thunderstorm. Too low
probability to insert in TAF.


.OUTLOOK FOR 06Z WEDNESDAY THROUGH THURSDAY...

.Late Tonight: Mainly VFR, but brief localized MVFR or lower
possible in a shower or thunderstorm. S-SW wind gusts 15-20 kt along
the coast.

.Wednesday: Mainly VFR, but brief localized MVFR or lower possible
in a shower or thunderstorm. SW wind gusts near 15-20 kt during the
day. Potential for SW wind gusts up to 25 kt along immediate coast
late day into early eve. Gusts 15-20 kt along coast at night.

.Thursday: Mainly VFR. S-SW wind gusts 15-20 kt. Gusts diminish at
night.

.Friday: Mainly VFR, but chances for MVFR or lower with chances of
showers and a slight chance of thunderstorms, afternoon into night.
SW-NW wind gusts 15-20 kt afternoon into evening.

.Saturday: Chance of showers and thunderstorms afternoon into night
with MVFR or lower possible at times.

&&

.MARINE...
A Small Craft Advisory is in effect for the western Long Island
Sound, NY Harbor, South Shore Bays and the ocean waters from
Sandy Hook to Fire Island Inlet out 20 NM. This is due to a
strengthening S/SW flow today that will bring 20 to 25 kt gusts
and brief 5 ft seas to the ocean waters.

Another SCA will likely be needed for most waters for Wednesday
afternoon through Wednesday night for a S/SW flow increasing to
25 kt again. Seas will also likely reach 5 to 6 ft.

Thereafter, conditions are expected to remain below SCA
conditions.


Rip Currents:

There is a moderate risk of rip currents today. While an onshore
flow strengthens, there is no significant wave component.
However, on Wednesday a 15 to 20 flow and 5ft 5s wind wave will
bring a high risk of rip currents.

&&

.CLIMATE...
Record High Temperatures:

July 1:
KEWR: 100/1963
KBDR: 95/1963
KNYC: 100/1901
KLGA: 97/2018
KJFK: 102/1963
KISP: 96/1964

July 2:
KEWR: 102/1966
KBDR: 100/1966
KNYC: 100/1966
KLGA: 101/1966
KJFK: 101/1966
KISP: 99/1966

July 3:
KEWR: 105/1966
KBDR: 99/1966
KNYC: 103/1966
KLGA: 107/1966
KJFK: 104/1966
KISP: 104/1966

July 4:
KEWR: 105/1949
KBDR: 98/1949
KNYC: 102/1949
KLGA: 100/1949
KJFK: 101/2010
KISP: 97/2010


Record High Minimum Temperatures:

July 1:
KEWR: 77/2018
KBDR: 73/2013
KNYC: 79/2018
KLGA: 79/2018
KJFK: 75/1968
KISP: 73/2025

July 2:
KEWR: 79/2022
KBDR: 73/2022
KNYC: 82/1901
KLGA: 78/2002
KJFK: 74/2018
KISP: 74/2014

July 3:
KEWR: 82/2002
KBDR: 75/2002
KNYC: 82/2002
KLGA: 81/1966
KJFK: 78/2002
KISP: 76/2018

July 4:
KEWR: 81/2002
KBDR: 80/2002
KNYC: 81/2002
KLGA: 82/1999
KJFK: 80/2002
KISP: 76/2002

July 5:
KEWR: 81/1999
KBDR: 74/2018
KNYC: 82/1999
KLGA: 86/1999
KJFK: 80/1999
KISP: 78/1999

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert from 11 AM this morning to 11 PM EDT this
     evening for CTZ005>007-009>011.
     Extreme Heat Warning from noon to 9 PM EDT Wednesday for
     CTZ005>007-009-010.
     Extreme Heat Watch from Wednesday evening through Saturday
     evening for CTZ005>007-009-010.
     Extreme Heat Watch from Wednesday afternoon through Saturday
     evening for CTZ008-011-012.
NY...Air Quality Alert from 11 AM this morning to 11 PM EDT this
     evening for NYZ069>075-176-178.
     Extreme Heat Warning from noon to 9 PM EDT Wednesday for
     NYZ067>075-176-178.
     Extreme Heat Watch from Wednesday evening through Saturday
     evening for NYZ067>075-176-178.
     Extreme Heat Watch from Wednesday afternoon through Saturday
     evening for NYZ078>081-177-179.
NJ...Air Quality Alert from 11 AM this morning to 11 PM EDT this
     evening for NJZ002-004-006-103>108.
     Extreme Heat Warning from noon to 9 PM EDT Wednesday for
     NJZ002-004-006-103>108.
     Extreme Heat Watch from Wednesday evening through Saturday
     evening for NJZ002-004-006-103>108.
MARINE...Small Craft Advisory from 2 PM this afternoon to midnight EDT
     tonight for ANZ335-338-345-355.

&&

$$

DISCUSSION...JT
AVIATION...JM
MARINE...JT

Previous Forecast Discussions may be found at
NWS New York City/Upton, NY (OKX) Office Forecast Discussions.
(Click 'Previous Version' there to view past versions successively.
Some may differ only in time posted.)

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