The summertime is ordinarily rather heat, with highs from eighty five °F (29 °C), to the minimal 100s (40 °C). The optimum recorded temperature in Glendale was one hundred fifteen °F (46 °C) on September 6, 2020. The cheapest recorded temperature was seventeen °F (−8 °C) on February 15, 1990. The warmest thirty day period is August and the coolest month is January. Todd VanDerWerff, Emily (January 21, 2010).