Half the year is over. Now that July is here, it’s time to look ahead at what the month brings climatologically to southwestern Connecticut. I'm sure you remember the record heat wave two years ago. The temperature climbed to 90 degrees July 14 and reached into the 90s the next six days for a seven-day heat wave. That was unprecedented across southwestern Connecticut. In fact, we also experienced a four-day heat wave from July 5 through July 8.
Not surprisingly, July is the warmest month of the year with a mean temperature of 74 degrees. The hottest temperature ever recorded at the airport happened July 22, 2011, when the mercury topped 103 degrees, tying the record originally set in 1957. The following day, July 23, 2011, another record high of 96 degrees was recorded.
The mercury reached the century mark two other times — July 2, 1966 and July 5, 1999. In fact, the average daily temperature climbs from 72 degrees at the start of the month to 75 by July 31. July of 2013 was the warmest on record with an average temperature of 78.5 degrees, breaking the previous mark of 78.4 degrees in 1994.
July of 2010 was another hot one. You may recall the heat wave over the Independence Day holiday weekend five years ago. The high temperatures from July 4 through July 7, 2010, were 97, 93, 98, and 95 degrees, respectively. In fact, record high temperatures were established July 6 and 7. The mercury also reached 95 degrees July 24. The average temperature for the month was 78 degrees, a half-degree shy of the all-time record set in 2013.
Many people have asked me why the hottest time of the year happens over a month after the first day of Summer. Well, it takes the Earth awhile to absorb the heat. As the Sun’s angle gets higher in the sky and the days grow longer in May and June, the Northern Hemisphere slowly starts to warm.
It’s much like warming your home. When you turn your thermostat up to 72 degrees after being away all day in the Winter, it will take awhile for the house to warm up. It doesn’t happen instantly. That’s why our hottest days are typically in July and early August.
On the flip side, the coolest temperature ever recorded in these parts in July was 49 degrees on July 1, 1988. Aside from that, every record low for the month is in the 50s. Believe it or not, according to the National Weather Service record book, a trace of snow fell at the airport on July 4, 1950. I find that too hard to believe.
As far as precipitation is concerned, the wettest July on record happened in 1971 when over a foot of rain (12.84″) fell. The average monthly rainfall is 3.77 inches. There have been several memorable rainstorms in July. For example, nearly a half-foot (5.95″) of rain fell on July 19, 1971, and nearly four inches (3.93″) was recorded on July 29, 1990. Two other days delivered well over three inches of rain — July 30, 1960 (3.57″) and July 23, 1953 (3.45″).
The length of daylight actually decreases this month. For example, today, the Sun rises at 5:23 and sets at 8:30. By the middle of the month, on July 15, the Sun rises at 5:32 and sets at 8:24. However, at the end of the month, it rises at 5:47 and sets at 8:10, meaning we lose 44 minutes of daylight. Remember, the “longest” day of the year happened at the Summer Solstice in late June.