You thought that with spring on the horizon, the freezing winter conditions were over, right? Well, that's not always the case.
Weather patterns fluctuate as the seasons start to change, and so there's no guarantee that things won't freeze over again before they get permanently warmer. This is known as the thaw-freeze cycle, and it's not an uncommon occurrence for things to warm up during the day and then freeze again at night.
This constant thawing and re-freezing can be a big contributor to so-called "black ice," which is nearly transparent and therefore hard to spot when driving. This makes driving on bridges and overpasses especially dangerous because they are so prone to overnight freezing.
So what do you do when it's constantly freezing and thawing out, and the ice is hard to spot? Reduce your speed and keep a safe distance from other motorists, for one. Also, know the conditions on the roadways before you set off on your trip. In addition, know the limits of your vehicle and don't try to exceed them.