Sierra Vista, AZ Monthly Weather | AccuWeather September 2023 Daily S M T W T F S 27 96° 69° 28 99° 72° 29 97° 69° 30 96° 71° 31 94° 70° 1 80° 67° 2 88° 64° 3 93° 67° 4 91° 67° 5 93°. For reference, on June 21, the hottest day of the year, temperatures in Sierra Vista typically range from 68°F to 93°F, while on January 3, the coldest day of the year, they range from 37°F to 59°F. Average High and Low Temperature in September in Sierra Vista Fall Link Download Compare Averages: J F M A M J J A Sep O N D.