Monsoon 2024: Tied Third Earliest Start

If you lived in Arizona before 2008, you likely remember everyone talking about the dew point to start the monsoon. Before 2008, the start date was determined based on Phoenix Sky Harbor having a delay average dew point of 55ºF or higher for three consecutive days. Since 2008, the start and end dates of the monsoon are fixed, from June 15th through September 30th, but we still like to track the dew point!

Using the old dew point rule, Monsoon 2024 started on June 21, 2024, after Phoenix Sky Harbor saw three days with a daily average dew point of 55º+ (June 21st: 55º, June 22nd: 60º, and June 23rd: 60º).

This is a very early start based on the dew point rule and tied as the third earliest start since records began in 1948. The average start date using the dew point rule is July 7th, with the earliest start occurring in 2000 on June 17th, and the latest being July 25th, set in 1987.

You can track the current dew points around the state HERE.