Maricopa County Cooperative Extension Home Horticulture:
Gardening & Landscaping in the Low Desert
Heat in the Valley of the Sun
When Does It Hit 100 degrees In The Valley?
This chart shows the dates that Sky Harbor Airport reached the first official 100 degree temperature from 1980 to 1996. For comparison, the chart shows the long term average 100 degree date. The earliest first 100 degree temperature was March 26, 1988. The latest was June 18, 1913. As the graph shows, only four of the last 16 years has the first 100 degree temperature equal to, or later than, the long term average.
In 1995, the first 100 degree day didn't occur until May 31. This was the latest first 100 degrees in over 15 years.
In our desert climate, heat causes more health problems than any other weather factor. Our soaring summer temperatures and low humidity can be a dangerous combination. Follow these rules to stay safe in the Arizona desert.
The heat wave of 1980 killed more than 1250 people in the United States. In the 40 years from 1936-1975, nearly 20,000 people have died from the effects of excessive heat. The only other weather related phenomena that kills more on the average each year is lightning.
The effects of heat on the body are known as heat stress. Many factors contribute to heat stress, but the most important elements influencing heat stress and comfort are temperature and humidity. As the chart indicates, the combination of high temperature and humidity greatly increases the threat for heat stress. The Apparent Temperature or Heat Stress Index assumes a very light breeze and you being in the shade. Of course, how hot "it feels" varies from one person to another, but this index seems to give a good idea of what the hot weather "feels like".
To find out what the air "feels like", use the table below. For example, with the air temperature of 90 degrees, and relative humidity of 60%, move down to where the columns meet and find the Heat Stress Index of 100 degrees.
Prolonged overexposure to the sun is the primary cause of skin cancer. Skin cancer is reported in 500,000 Americans each year and 6,500 to 7,500 cases result in death. That is more deaths per year than all other weather factors combined, including tornadoes, hurricanes, heat waves and winter storms. Fortunately, 95% of skin cancer patients are free of the disease once treated. The cure rate would approach 100% if everyone with symptoms sought prompt medical attention.
See your doctor if you see any of these or other changes on your skin you can't explain or which last for than 30 days.
The Arizona Cancer Center
Arizona Sun Awareness Project
Cancer Cope Line 1-800-622-COPE
® Copyright 1997 by Ed Phillips/KTAR Radio. Information provided courtesy of KTAR via Ed Phillips Arizona Almanac.
Heat in the Valley of the Sun
visitors since April 10, 1998 Last Updated July 22, 1998
Author: Cathy Rymer, Administrative Secretary, University of Arizona Cooperative Extension, Maricopa County
Reviewed by: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture, Cooperative Extension, in Maricopa County
Comments to Cathy Rymercrymer@ag.arizona.edu 4341 E. Broadway Rd., Phoenix, AZ 85040
(602) 470-8086 ext. 308