Normal defines something as standard, typical, or average, conforming to a regular pattern rather than being abnormal or unusual. It refers to actions, states, or measurements that fall within expected, natural, or healthy limits. As a noun, it refers to the standard condition, or in math, a line perpendicular to another. [1, 2, 3, 4, 5, 6, 7]
my interpretation in this instance: A typical spring back and forth temperature pattern with frequent bouts of rain, and thunderstorms including some early spring snow events. Interspersed with some spectacular weather days reminding one summer will soon be here in all its beautiful grandeur.