Tomorrow is the vernal equinox, which means it's the first day of spring! From tomorrow until the summer solstice on June 21, the days will get longer and warmer. This is due to the way the sun hits the surface of the earth. Tomorrow, the sun will be shining directly onto the equator. Then, the sun will shine directly above latitudes farther to the north until the solstice. That is why the days will get longer and warmer.
So, happy spring!