Tucson’s Climate and the Monsoon
Tucson is celebrated as one of the sunniest cities in the United States with more than 350 days of sunshine every year. It offers a hot, semi-arid steppe climate and is known for its “dry” heat, which is the result of a lack of humidity in the air. Tucson averages less than 25% humidity each year leaving residents and visitors alike to enjoy the beautiful sunshine and outdoors.
The average daily temperature in Tucson is a balmy and perfect 83°. November through March is considered Tucson’s cold season. During these months, residents see an average temperature below 71° each day with lows in the high 30s. Tucson’s hot season runs from May 28 to September 13 with average daily temperatures of 95° or higher. The rest of the year, the temperatures are mild and the sun shines with rarely a cloud in the sky.
Due to Arizona’s constant sunshine and beautiful climate, people tend to spend a significant amount of time in the great outdoors. It is imperative that those enjoying the great outdoors follow a few simple rules such as wearing a hat and sunscreen, which must be reapplied every couple of hours. It is also very important to drink plenty of fluids, particularly water. To avoid dehydration, one should drink at least one liter of water every hour. Freezing a bottle of water to take on excursions is one popular method for helping to keep cool. Many people also take advantage of the cooler early morning hours to get out for hiking, biking and jogging before the day heats up.
One of the unique things about Tucson is the monsoon season, which typically occurs between June 15 and September 30 each year. The rather impressive thunderstorms during this time produce nearly half of the annual precipitation in Tucson or about 6 inches of rainfall each monsoon season. Typically the days start off warm and sunny during this time with thunderheads rolling in during the early to late afternoon. Spectacular lightening often accompanies these monsoon thunderstorms turning the sky into an amazing natural electric light show.
The word monsoon comes from the Arabic word mausin meaning “wind shift” or “season” and refers to a seasonal shift in the wind, which produces precipitation as a result. A monsoon is a thunderstorm caused by warm air creating low-pressure zones that in turn draw moist air from the oceans. The winds in Arizona typically come from the west but a shift to a southeasterly wind in the summer can bring moisture from the gulfs of Mexico or California. The wind shift and increased moisture combined with the low surface pressure produces storms in a cycle of “bursts” of heavier rainfall and “breaks” of lighter rainfall. The shift in the wind may also trigger an event known as a haboob. These appear occasionally just before the rain and are a wall of loose, swirling dust that can be up to several hundred feet in height.
While the monsoon rains bring a beautiful blooming of life to the Sonoran Desert, they can also create dangerous flash flood conditions. In just a few minutes, natural rivers and washes, underpasses, bridges and streets may become unpassable during the storms or just after. Warning signs are posted in many areas warning if there is a danger of flooding, but each year motorists are stranded or worse due their attempts to drive through the water. A good rule of thumb is to avoid driving through a wash or street with water that appears to be larger than your car or a swimming pool. It is simply best to take an alternate route when water is in the way.