The National Weather Service is warning of the chance of rain and thunderstorms today in what looks like an otherwise sunny and warm day today.

A weak system passing north of the border will spark a brief period of showers and possibly a few isolated rumbles of thunder early this afternoon in St. Lawrence County, the NWS predicts.

Aside from that, we can expect mostly sunny skies and highs in the mid-60s today.

Tonight under clear skies, the temperature will drop below the freezing point.

Another sunny day is in store for Sunday, with highs again in the mid-60s.

Clouds will move in Sunday night, the NWS says, and a period of rain begins.

Monday into early Tuesday, moderate rainfall is expected that may result in rises on area streams and rivers. Strong gusty winds are expected to occur in the higher terrain of the Adirondacks.

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

• Today: A chance of showers before noon, then showers likely and possibly a thunderstorm between noon and 1pm. Mostly sunny, with a high near 63. West wind 13 to 16 mph, with gusts as high as 29 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

• Tonight: Mostly clear, with a low around 29. North wind 6 to 13 mph.

• Sunday: Sunny, with a high near 63. Northeast wind 6 to 8 mph.

• Sunday Night: Showers likely, mainly after 5am. Increasing clouds, with a low around 39. Southeast wind 8 to 13 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

• Monday: Rain, mainly before 1pm. High near 56. Southeast wind 14 to 18 mph, with gusts as high as 32 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

• Monday Night: Rain, mainly after 7pm. Low around 46. Southeast wind 8 to 14 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

• Tuesday: A 50 percent chance of rain. Mostly cloudy, with a high near 58. Southwest wind 7 to 11 mph.

• Tuesday Night: A 30 percent chance of showers. Mostly cloudy, with a low around 40. Southwest wind 7 to 9 mph.

• Wednesday: A 40 percent chance of showers. Mostly cloudy, with a high near 52. Southwest wind 9 to 11 mph.

• Wednesday Night: A 30 percent chance of showers. Mostly cloudy, with a low around 35. Southwest wind around 8 mph.

• Thursday: A 40 percent chance of showers. Mostly cloudy, with a high near 50. West wind 8 to 10 mph.

• Thursday Night: A 30 percent chance of showers. Mostly cloudy, with a low around 34. West wind around 7 mph.

• Friday: A 40 percent chance of showers. Mostly cloudy, with a high near 50. West wind 8 to 10 mph.