I remember a few mornings it being very chilly. We are headed back here in a few weeks and bringing tents this time. We are prepared with electric blankets and heaters but still worried about getting cold at night. Last January was abnormally cold and worried we will have the same low temps as last trip. Days were great, just the nights were chilly.
Nights can definitely be chilly in Jan/Feb. We don't take sleeping bags, just ThermoAir 'camping quilts'. Generally we've been comfortable (but we're also pretty hardy. We keep the house much colder than most folks would.) We did pick up a cheap electric heater at a yard sale this year, which we'll be bringing along just in case we have one of those abnormally cold nights like you've mentioned.
I'd say you'd have to answer your question yourself, especially if you're familiar with the possible temps. It all depends on your tolerance for cold, how warm your bedding is, etc.