The map is original work of Jim Irwin, December 2006. It is based on the 1971-2000 normal July daily maxmimum temperature data from the PRISM Group, Oregon State University, <a rel="nofollow" class="external free" href="http://www.prismclimate.org">http://www.prismclimate.org</a>, created 4 Feb 2004.
The original uploader was <a href="https://en.wikipedia.org/wiki/User:JimIrwin" class="extiw" title="wikipedia:User:JimIrwin">JimIrwin</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>.
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