Federal Highway Administration Aurora Program Transportation Pooled Fund (TPF SPR-3(042))
Iowa Department of Transportation
RWIS Coordinator, Iowa Department of Transportation
About the research
Weather indices are powerful tools that can help observers quantify the severity of a winter season and allow comparison of the severity from one region or year to another. Such comparisons provide very useful information for those studying winter maintenance costs or other department of transportation (DOT) functions that are influenced by weather. While weather indices can be powerful tools, they must be used appropriately. An agency must select the right weather index for the job and have the data needed to compute the chosen index.
This guide describes weather indices in general, shows how they are used and misused, refers to some existing indices and identifies the data needed for computations, and presents an example showing how to use an index to understand other winter maintenance issues.