From the Spaceflight Meteorology Group:

Temperatures at JSC will be dropping down in the mid 30s Friday morning and lower 30s on Saturday morning.  Forecast low temperature is 34 Friday morning and 32 on Saturday morning at JSC. Any freezing temperatures at JSC, if that occurs, would only last about 1 to 3 hours each morning.

Some cold very light rain is likely this afternoon into the evening hours from time to time.  Accumulation if forecast to be under 0.05 inch.  Better chances for rain are off to the south and southwest of JSC / Houston. Drier air near the surface starts filtering in from north late this evening shutting down our rain chances.  There still remains a very meager chance for a few pellets of sleet before sunrise, not enough to cause any travel problems near JSC.  Any wintry weather would be on the order “blink and you’ll miss it” if it occurs.