Where can I get archived hourly temperature data?
The authoritative sources for your data are:


ASOS: Automated Surface Observation Systems at airports, and
MADIS:  the Meteorological Assimilation Data Ingest System, from NOAA


Those are collections based on calibrated, maintained equipment, with good geographic coverage.

And Wunderground already archives them, so it's a matter of selecting and using those, rather than the Wunderground data from their own source, the collection of personal weather stations.