FZUS81 KBUF 170236 ICESL Saint Lawrence Freeze Up Date Outlook National Weather Service Buffalo NY 936 PM EST Mon Dec 16 2024 ...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 5, 2025. WATER TEMPERATURES... Water temperatures had been running well above average across the eastern basin of Lake Ontario and the Saint Lawrence River through most of the fall. Several stretches of below normal air temperatures through the first half of December have removed much of the excess warmth, with water temperatures in the upper Saint Lawrence River now near average for mid December. Water Temperatures December 16th: Alexandria Bay, NY 42F (normal 42F) LAKE ONTARIO OUTFLOW... The outflow from Lake Ontario has averaged around 238,000 CFS over the past few days, which is very close to the long term average for this time of year. Near to slightly below average outflow from Lake Ontario is likely to continue through the rest of December. AIR TEMPERATURES... Temperatures were mild and above average on the whole through the fall. September through the first few days of October were consistently above average most of the time, resulting in much warmer than normal water temperatures heading into mid fall. October was more of a mixed bag, with an extended period of temperatures near to below average during the second and third week of the month. This trend turned around for the last 10 days of the month, with several stretches of well above average temperatures, including record warmth on the last two days of the month. The first half of November has continued the trend of above normal temperatures, with a half dozen very warm days intermixed with several slightly below normal days. Temperatures have been on a roller coaster ride from late November through the first half of December, with stretches of quite cold weather trading with stretches of near to slightly above average temperatures. Overall, temperatures have been colder than average since late November. December Average Air Temperatures through December 16th: Watertown, NY 26.4F (3.4F below normal) Massena, NY 24.9F (1.7F below normal) FORECAST FOR THE REST OF DECEMBER... Above normal temperatures for the next few days will be replaced by another push of cold air late this week through early next week. The cold will only last for 3 or 4 days, then will be replaced by well above normal temperatures starting around Christmas Eve and lasting through the end of the month. Another push of colder air may arrive around New Year's Day, but this too may lack staying power. A weak La Nina pattern is expected this winter. This pattern may allow for other, more difficult to predict circulations to have more influence on the winter pattern across central and eastern North America. Overall, trends favor above normal temperatures through the end of December, then a better chance of more typical and consistent winter cold developing in January and lasting into February. 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 5, 2025. This date is around two weeks 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