The National Weather Service says there is a 50 percent chance thunderstoms could hit Potsdam and Star Lake tonight, with a 30 to 40 percent chance for other communities in St. Lawrence County.

The odds tonight drop to 30 percent countywide, with skies predicted to clear later on. Temperatures are predicted to drop from the high 80s during the day to the high 60s at night.

Tuesday is forecast to be warm, with temperatures in the low- to mid-80s with a 50 percent chance of thunderstorms during the day.

That gives way to a 70 percent chance of showers at night in Canton, Gouverneur, Potsdam, and Massena with thermometers reading in the high 50s.

Wednesday and Thursday should be clear with temperatures in the 70s, the NWS said.

The detailed forecast for Potsdam:

This afternoon - A 50 percent chance of showers and thunderstorms. Partly sunny, with a high near 88. Calm wind. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tonight - A 30 percent chance of showers and thunderstorms, mainly before 8pm. Mostly clear, with a low around 69. South wind 3 to 7 mph. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Tuesday - A slight chance of showers between noon and 1pm, then a chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. South wind around 8 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tuesday night - Showers likely and possibly a thunderstorm before 2am, then a chance of showers. Mostly cloudy, with a low around 60. Light and variable wind becoming north 5 to 7 mph after midnight. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Wednesday - Cloudy through mid morning, then gradual clearing, with a high near 72. North wind around 9 mph.

Wednesday night - Mostly clear, with a low around 52. Northeast wind around 6 mph.

Thursday - Sunny, with a high near 76. North wind 5 to 7 mph.

Thursday night - Mostly clear, with a low around 55. Light and variable wind.

Friday - Mostly sunny, with a high near 82. Calm wind becoming south around 5 mph in the afternoon.

Friday night - A 30 percent chance of showers after 2am. Mostly cloudy, with a low around 63. Calm wind becoming south around 6 mph after midnight.

Saturday - A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 82. Southwest wind around 8 mph.

Saturday night - A 30 percent chance of showers. Mostly cloudy, with a low around 64. Southwest wind 3 to 6 mph.

Sunday - A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 82. Calm wind becoming west around 6 mph in the morning.

Sunday night - Mostly cloudy, with a low around 65. South wind 3 to 5 mph.

Monday - A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 83. South wind around 7 mph.