by Article Writer
November was relatively cool and dry. The only day with recorded rainfall was the last day of the month. Most of the Vail area received 0.1 to 0.4 inches. I recorded 0.23 inches, which is about one-half my eight-year November average of 0.48 inches. The Tucson airport recorded 0.07 inches, which is well below its 30-year average of 0.57 inches. November 2018 was over 9 degrees cooler on average than November 2017, when Tucson recorded its warmest November since the 1880s. November 2018 was one-tenth of a degree below the airport’s 30-year average.
With October and November having below average temperatures, 2018 slipped one more notch to the 4th warmest year on record for Tucson so far. The climate prediction center is still forecasting better than average chances for above normal temperatures and rainfall for the three winter months due to a mild El Nino. Since November was a relatively boring month for weather, I would like take the time to define and discuss the urban heat island. An urban heat island (UHI) is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. This is mainly caused by changes to the land surface such as concrete, pavement, rooftops, and more. This is most pronounced at night when “the city” does not cool off as fast or as much as the surrounding areas. Also, this is more pronounced with drier air, than humid air.
One of the reasons I moved to Vail was to get out of the heat island of Tucson. I can open my windows sometimes at night in early June in Vail where, when I lived in town, it was still too warm to do so. Many times, in the early evening, when I leave town and come home to Vail, the temperature is 5 to 10 degrees cooler in Vail. One time I noticed an 18-degree cooldown from downtown Tucson to my home in just a 25-minute drive in April. Since November was basically cool and dry, I looked at the daily temperature data from Douglas, AZ and Tucson, AZ airport. Tucson recorded 19 days of at or above average daily temperatures and Douglas recorded only 10. So, two-thirds of Tucson’s November days were at or above average and only one-third of the days in the more rural Douglas area. These were compared to 30-year averages and in that time, Tucson had grown substantially while Douglas had not. Next month we will examine December’s weather and the stats for the entire year.
