While monsoon season officially begins on June 15, the arrival of the North American Monsoon is unpredictable, as it varies from year to year. On average, Tucson receives its first monsoon storms around July 3. Monsoon activity generally persists through August and often into September.NWS Tucson Office Monsoon tracker . Retrieved March 12, 2010. During the monsoon, the humidity is much higher than the rest of the year. It begins with clouds building up from the south in the early afternoon, followed by intense thunderstorms and rainfall, which can cause flash floods. The evening sky at this time of year is often pierced with dramatic lightning strikes. Large areas of the city do not have storm sewers, so monsoon rains flood the main thoroughfares, usually for no longer than a few hours. A few underpasses in Tucson have "feet of water" scales painted on their supports to discourage fording by automobiles during a rainstorm.Two underpasses leading towards downtown Tucson from the north, at Sixth Avenue and Stone Avenue, have such "feet of water" scales. Arizona traffic code Title 28–910, the so-called "Stupid Motorist Law", was instituted in 1995 to discourage people from entering flooded roadways. If the road is flooded and a barricade is in place, motorists who drive around the barricade can be charged up to $2000 for costs involved in rescuing them.Arizona State Legislature, ARS 28–910, Liability for emergency responses in flood areas; definitions . Retrieved March 12, 2010. Despite the warnings and precautions, three Tucson drivers have drowned between 2004 and 2010.
While monsoon season officially begins on June 15, the arrival of the North American Monsoon is unpredictable, as it varies from year to year. On average, Tucson receives its first monsoon storms around July 3. Monsoon activity generally persists through August and often into September.NWS Tucson Office Monsoon tracker . Retrieved March 12, 2010. During the monsoon, the humidity is much higher than the rest of the year. It begins with clouds building up from the south in the early afterno,on, followed by intense thunderstorms and rainfal!l, which can cause flash floods. The eveni?ng sky at this time of year is often pierced with dramatic lightning strikes. Large areas of the city do not have storm sewers, so monsoon rains flood the main thoroughfares, usually for no longer than a few hours. A few underpasses in Tucson have "feet of water" scales painted on their supports to discourage fording by automobiles during a rainstorm.Two underpasses leading towards downtown Tucson from the north, at Sixth Avenue and Stone Avenue, have such "feet of w?ater" scales. Arizona traffic code Title 28–910, the so-called "Stupid Motorist Law", was instituted in 1995 to discourage people from entering flooded roadways. If the road is flooded and a barricade is in place, motorists who drive around the barricade can be charged up to $2000 for costs involved in rescuing them.Arizona State Legislature, ARS 28–910, Liability for emergency responses in flood areas; definitions . Retrieved March 12, 2010. Despite the warnings and precautions, three Tucson drivers have drowned between 2004 and 2010.