The National Weather Service (NWS) has issued a severe thunderstorm warning for St. Lawrence County with large hail, 60 mph winds and dangerous cloud to ground lighting are expected.

A severe thunderstorm was located over Jacques Cartier State Park in Ontario moving east at 40 mph, the service says.

Quarter-sized hail is expected and will likely damage vehicles, roofs, and siding, NWS says. Winds could cause damage to trees as well.

The NWS advises people to move to an interior room on the lowest floor of the building for safety precautions. Lighting is one of nature’s leading killers, the service says.

The towns likely to impacted by the storm include Ogdensburg, Canton, Norfolk, Madrid, Norwood, Colton, Heuvelton, Edwardsville, Morley, Lisbon, Pierrepont, Parishville, DePesyter, West Stockholm, Hannawa Falls, Hammond, Morristown, Resnsselaer Falls, West Potsdam and West Parishville.

The sever thunderstorm watch is in effect from 11:15 a.m. until 8 p.m.

Highs today will be near 85 degrees and overnight lows will drop to around 57 degrees, NWS says.

Things will dry up and be slightly cooler on Tuesday. Highs will be near 73 with winds of 5 to 8 mph, NWS says.

The forecast through the weekend is as follows:

Tuesday

Sunny, with a high near 73. Calm wind becoming northwest 5 to 8 mph in the afternoon.

Tuesday Night

Mostly clear, with a low around 53. Northwest wind around 6 mph becoming calm in the evening.

Wednesday

Sunny, with a high near 80. Calm wind becoming west around 6 mph in the afternoon.

Wednesday Night

Mostly clear, with a low around 60. Southwest wind 3 to 6 mph.

Thursday

Mostly sunny, with a high near 85. Southwest wind 7 to 11 mph.

Thursday Night

A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 69. Southwest wind around 9 mph.

Friday

A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 87. Southwest wind around 9 mph.

Friday Night

A chance of showers and thunderstorms. Mostly cloudy, with a low around 68. Southwest wind around 6 mph. Chance of precipitation is 40%.

Saturday

A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 86. West wind around 7 mph.

Saturday Night

A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 67. Calm wind becoming southwest around 5 mph after midnight.

Sunday

A 40 percent chance of showers. Mostly sunny, with a high near 84. West wind around 6 mph.