Cool summer: June highs average 100

The National Weather Service is confirming what Valley residents already knew: This June was notably cooler than usual.

Daily high temperatures last month averaged 100 degrees, which is 3.9 degrees lower than normal. Looking at the records kept in the Valley since 1896, this tied for the 27th coolest June. Also, it was the coolest since 1998, when June's average high was 98.7 degrees.

There were 15 straight days when the temperature failed to reach triple digits. This tied as the third-longest streak of sub-100 June days on record; the longest stretch was 17 days in 1913.

In addition, between June 6-19 the average high was 95.3 degrees, making it the coolest two-week stretch in June since 1999.

Responsible for this cooling trend was a series of low-pressure systems off the Southern California coast. Those systems would occasionally send pulses of clouds and humidity into Arizona, which helped keep down temperatures.

But that same cloud cover acted as an insulating blanket during the nights. The average low temperature of 77.4 degrees - above normal by 1.8 degrees - was the 19th warmest June on record. Still, these were the coolest June nights since 1998.