It's Spring... But It Doesn't Feel Like It!

I woke up this morning and looked out the door and my dog's water bowl's water was frozen on top. How could this be? Just a week or two ago it felt like spring - and now this week - the first week of spring - it feels like winter again. The low was around 30 degrees last night. The high today is supposed to make it up to the mid 50's I think. A week ago it was 75 degrees outside! Strange, strange Tennessee weather.