There were plenty of thunderstorms yesterday, and hopefully there will be more today, as the monsoons have arrived here in Tucson. Early in the day, the clouds are white and puffy, and this nice cloud even seemed to be giving me a friendly wave hello.

These harmless-looking clouds gradually change their character as the day progresses. They grow, bulging upward and outward, coalesce, darken, and turn ominous by afternoon, forming powerful monsoon thunderstorms. These thunderstorms are often violent, and while tornados are very rare, frequent lightning, high winds, and heavy rain resulting in dangerous flash flooding are common. People have drowned here in Tucson while trying to drive across flooded washes. I was once trapped at someone's house for hours after a bad thunderstorm because every road out was flooded.

Despite their dangers, the monsoons are eagerly anticipated here in Tucson because they provide much needed rain and moderate the blazing summer temperatures. The monsoons officially started here in Tucson on Monday, July 18, the second latest start on record. On July 22, Tucson tied the 1987 record for consecutive 100 °F (37.8 °C) or higher days at 39 days. Thankfully, this streak ended when July 23 did not make it to 100 °F.