Here in Southern Utah, April can range from beautiful and warm, with the sun shining and no need for a jacket at all, to beautiful and cold with blizzard conditions.
We are located perfectly between two national parks: Zion & Bryce Canyon. Zion is typically 10-20 degrees warmer than Bryce Canyon, but both can be quite unpredictable.
Point is, when you come to ride bring a good coat and pair of mittens with you, even if you just end up leaving them in your vehicle or tied to the back of your saddle.
Remember: "There's no such thing as bad weather, only bad clothes!"