Temperatures warm back into the lower 90s today with increasing humidity values before a cold front brings chances of thunderstorms across the St. Lawrence Valley this afternoon and evening, according to the National Weather Service (NWS).

The heat and humidity, combined with an approaching cold front will produce scattered to widespread afternoon and evening showers and thunderstorms, the service says. The primary threat will be lightning and brief heavy rainfall.

Overnight lows will be around 55 with a 30% chance of rain or thunderstorms, forecasters say.

Skies will be sunny Saturday but temperatures will be much cooler, with highs barely reaching 70, the service says.

The extended forecast through Thursday is as follows:

Saturday

Sunny, with a high near 69. Northeast wind 11 to 13 mph.

Saturday Night

Mostly clear, with a low around 46. Northeast wind 3 to 8 mph.

Sunday

Sunny, with a high near 71. Northeast wind 6 to 9 mph.

Sunday Night

Increasing clouds, with a low around 50. Northeast wind around 7 mph becoming south after midnight.

Monday

A 50 percent chance of showers after 2pm. Mostly cloudy, with a high near 67. Southwest wind 9 to 13 mph becoming west in the afternoon.

Monday Night

A 50 percent chance of showers. Mostly cloudy, with a low around 51. Northwest wind 7 to 9 mph.

Tuesday

Showers likely, mainly after 2pm. Partly sunny, with a high near 64. North wind 9 to 13 mph. Chance of precipitation is 60%.

Tuesday Night

Showers likely, mainly before 8pm. Mostly cloudy, with a low around 49. North wind 8 to 10 mph. Chance of precipitation is 60%.

Wednesday

A 50 percent chance of showers. Partly sunny, with a high near 66. North wind 8 to 13 mph.

Wednesday Night

A 30 percent chance of showers. Mostly cloudy, with a low around 49. North wind 7 to 10 mph becoming west after midnight.

Thursday

A 40 percent chance of showers. Partly sunny, with a high near 68. Northwest wind 8 to 10 mph.