Monday, Aug. 2, 2010 | 9:37 p.m.
July in Las Vegas entered the record books as the warmest month in recorded weather history.
The mercury reached the triple digits each day in a month for the ninth time since records were kept beginning in 1937. But in addition to above-average high temperatures, forecasters said higher low temperatures were a main factor in the record-breaking heat.
The average temperature last month at McCarran International Airport was 96.2 degrees, which is 5 degrees warmer than average. The previous record for the warmest month ever was in July 2007 with an average temperature of 95.4 degrees, according to National Weather Service records.
The average low temperature in July was 85.7 degrees, which set a record for the warmest average low during any month in the city's recorded history. The month also set a record for having six days with lows of at least 90 degrees.
The low of 93 degrees on July 19 tied for the third-highest low temperature ever in Las Vegas.
Forecasters said the average high temperature during the month was 106.6 degrees, which ties for the 13th warmest in Las Vegas. The last time the city recorded at least 100 degrees each day in a month was July 1988.
July's warmest days were the 15th and 18th, both of which saw the mercury reach a sweltering 113 degrees, the weather service said.
The coolest high and low temperatures in the month were on July 4, which saw readings of 100 degrees and 77 degrees.
"While the intensity of the heat during the middle portion of July 2005 was worse, that month managed to see a break in the heat toward the later part of the month as monsoonal moisture moved in," the weather service said in a statement. "This July, monsoonal moisture did move in during the close of the month but brought in a decent amount of cloud cover that kept up temperatures at night."
July was also dry: McCarran recorded only a trace of rainfall during the month, forecasters said. Measurable rainfall in parts of Henderson on July 30 didn't make its way to the valley's official reporting station at McCarran.
The last time Las Vegas saw a high temperature fall short of 100 degrees was June 22, which topped out at 98 degrees. The triple-digit heat will continue, with highs between 104 and 106 degrees in the forecast each day through the weekend, the weather service said.