National Oceanic and Atmospheric Administration (NOAA) METAR sites at Phoenix metro area airports.
They usually update between ten till and the top of the hour, Glendale doesn't at night. So they should update here at beginning of each hour. METAR is an international standard Aviation Routine Weather Report code. The reports are primarily collected by equipment such as Automated Surface Observing Systems (ASOS). In the code the time is given in ZULU UTC, wind in Knots, and temperatures in centigrade. VWS creates these icons from the coded METAR text code which looks like this: