A Hazardous Weather Outlook warning has been posted by the National Weather Service for St. Lawrence County for predicted showers and thunderstorms today and tonight, and possibly extending into Sunday and Monday.

The NWS says there is a 60 to 80 percent chance of showers and thunderstorms this afternoon and a 90 to 100 percent chance tonight, with highs today in the 80s and lows tonight around 50.

The NWS warns that storms could produce localized heavy rainfall and isolated gusty winds this afternoon and evening. Gusts could exceed 30 mph. Some minor poor-drainage flooding is possible in the heavier thunderstorm activity, NWS says.

Sunday and Monday, additional showers with embedded thunderstorms will continue, producing more rainfall with a continued threat for minor flooding.

Sunday and Sunday night will be cool, with temps in the 50s under cloudy skies.

Right now, the forecast is for a continuing chance of showers through Tuesday with cooler than average temperatures before clearing and warming up for the rest of the week.

The NWS forecast for the St. Lawrence Valley and northwestern Adirondacks:

• Today: A chance of showers, then showers and thunderstorms likely after noon. Some of the storms could produce gusty winds and heavy rain. Mostly cloudy, with a high near 81. Breezy, with a southwest wind 16 to 20 mph, with gusts as high as 32 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

• Tonight: Occasional showers and thunderstorms before midnight, then occasional showers and possibly a thunderstorm, mainly after midnight. Some of the storms could produce heavy rain. Low around 50. Southwest wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

• Sunday: Showers likely and possibly a thunderstorm before 9am, then a chance of showers. Cloudy, with a steady temperature around 53. Northeast wind around 11 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

• Sunday Night: Showers likely, mainly after 10pm. Mostly cloudy, with a low around 49. Northeast wind around 9 mph. Chance of precipitation is 60%. New precipitation amounts between a quarter and half of an inch possible.

• Monday: Showers likely. Cloudy, with a high near 62. Northeast wind around 11 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

• Monday Night: A 50 percent chance of showers. Mostly cloudy, with a low around 51. East wind 6 to 11 mph. New precipitation amounts between a tenth and quarter of an inch possible.

• Tuesday: A 40 percent chance of showers. Mostly cloudy, with a high near 61. East wind around 6 mph becoming calm in the afternoon.

• Tuesday Night: Mostly cloudy, with a low around 49. Calm wind.

• Wednesday: Mostly sunny, with a high near 71. West wind 3 to 5 mph.

• Wednesday Night: Partly cloudy, with a low around 54. South wind 3 to 7 mph.

• Thursday: Mostly sunny, with a high near 78. Southwest wind around 8 mph.

• Thursday Night: Partly cloudy, with a low around 58. Southwest wind around 7 mph.

• Friday: Partly sunny, with a high near 79. West wind around 8 mph.