Figure 1 provides an overview of Washington State mean Freezing Index (FI) data (summarized for 1951 to 1980). Figure 2 is a contour map of Washington for design FI data. WSDOT uses The FI contours for both figures are only approximate. FIs should be obtained at specific sites (projects) if possible.
Figure 1: Mean Freezing Indicies
Figure 2: Design Freezing Indicies