Unless you get a hard feeze (20 degrees or less) for an extended period of time (several days), you will probably be safe in just opening the cabinet doors under the sinks and allowing the warm air to circulate around the pipes.

I don't become concerned until the forecast calls for temps below 10 to 15 degrees for 2 or 3 days. Then I just allow the faucet to barely drip to let the warmer (60 + degrees) water keep the pipes open

 

Dont mean to argue with JimD, but...

Dont mean to argue with JimD, but...several days of weather in the below freezeing, can freeze outdoor water lines and faucets. This freeze wont do it, but you should wrap outdoor faucets with insulation, and bring in water hoses in extreme cold--some will streatch, some wont. Dont forget your outboard. We have not even had to think about it in quite a few years, but guess what can happen to water in your water jackets and water pump if you get several days of REALLY cold weather and your outboard is not protected? The water from your last trip or flushing normally does not evaporate away real fast.

Later
R3F