IIIa. SWD Development Maps

These maps are created daily from degree-day models run for thousands of locations which are combined with PRISM Climate maps. This gives a very localized yet wide-ranging prediction of development. The legends are also created daily and so these maps cannot be compared over time - see Monthly Phenology Maps below for a series of maps that can be compared over time. These maps show year to date stages of development, mainly highlighting first spring egg-laying and number of generations. The series for differences from normals indicates which parts of the country have cooler (delayed development) and warmer (advanced development) comparing this years degree-day accumulations with 30-year normals.