The average gap between daytime and nighttime temperatures in Arizona has declined by about two degrees since 1930.
Daytime temperatures have dropped by more than two degrees, but nighttime temperatures have not dropped as much, due to well documented Urban Heat Island effects
The National Weather Service did a study showing how daytime and nighttime temperatures have diverged between Phoenix and nearby rural locations.
National Weather Service – NWS Phoenix
Alarmists blame increasing minimum temperatures on CO2, because their brains are slightly less functional than those of celery stalks.
Steven , celery stalks everywhere are insulted as at least they grow and produce something usefull.