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FZUS81 KBUF 011329
ICESL

Saint Lawrence Freeze Up Date Outlook
National Weather Service Buffalo NY
929 AM EDT Sat Nov 1 2025

...FREEZE-UP DATE OUTLOOK FOR THE SAINT LAWRENCE RIVER...

The date of the first freeze-up on the Saint Lawrence River near
Massena, NY is forecast to be January 1, 2026.

WATER TEMPERATURES...

Water temperatures had been running above average across the eastern
basin of Lake Ontario and the Saint Lawrence River through the first
half of fall. The warm lake and river temperatures were driven by
long stretches of above average temperatures and very dry weather
from September through the first three weeks of October.

Water Temperatures October 30th:

Alexandria Bay, NY   58F (normal 55F)

LAKE ONTARIO OUTFLOW...

The outflow from Lake Ontario has averaged around 236,000 CFS over
the past few days, which is slightly below the long term average for
this time of year. Outflow from Lake Ontario into the Saint Lawrence
River is expected to be below average through November. Below
average outflow can reduce the speed of the current in the river and
allow ice to more readily form.

AIR TEMPERATURES...

Temperatures were warm much of the time from September through the
first 3 weeks of October, with numerous stretches of very warm days.
Very dry weather through much of the fall also minimized runoff of
cool water into the lakes. Recently, the pattern has turned much
cooler, with temperatures running slightly below average for the
last week of October. The pattern has also turned more active, with
numerous rain events bringing increased runoff to close out the
month.

October Average Air Temperatures through October 29th:

Watertown, NY   50.3F (1.2F above normal) Massena, NY     50.3F
(2.5F above normal)

FORECAST FOR NOVEMBER...

Below average temperatures will persist through the first week of
November across the Saint Lawrence Valley. The persistent cool
weather from late October through early November will likely remove
much of the excess warmth from Lake Ontario and the Saint Lawrence
River, allowing water temperatures to approach average values. Above
average temperatures are then favored to return starting the second
week in November and lasting through the middle of the month.

A weak La Nina pattern has developed in the equatorial Pacific
Ocean, and is favored to continue through the first half of winter
before weakening by late winter or early spring. Weak or neutral
conditions in the Pacific Ocean can allow for other, more difficult
to predict circulation patterns to have greater influence on the
weather in the Great Lakes. The long term outlook shows equal
chances for above, below, or near average temperatures through the
winter in the lower Great Lakes and Saint Lawrence Valley.

Given the above factors, and the overall trend in later onset of ice
cover over the past 15 years, the first freeze-up on the Saint
Lawrence River near Massena, NY is forecast to be January 1, 2026.
This date is around 10 days later than the long term average.

NOTE: Once the water temperature drops to the mid 30s, ice cover can
develop in just one very cold, calm night.

NOTE: This forecast is for the first shore to shore freeze-up of the
Saint Lawrence River near Massena, NY. The first permanent shore to
shore ice often occurs several weeks later.

$$

Hitchcock