Blue Hill Observatory
July 2015 Summary:
The month was notable for being warm and mostly dry with more sun than average. The 24-hour mean temperature for the month of 72.4 deg F was 2.7 degrees warmer than the 120-year average for July, and about one degree warmer than the 1981-2010 30-year average. The maximum temperature for the month was 92F on the 29th, and the coolest temperature was 56F on the 16th and 17th. There were only two days that reached 90 degrees or higher in July, and these have been the only 90-degree days so far in 2015. The first 90-degree day of the year occurred on 20 July, which was later than the date of the first 90-degree day in 2014 of 3 July. The last time the first 90-degree day was later than this was on 23 July 1998. There have been only six 90-degree days over the last two years from 1 August 2013 through 31 July 2015. The minimum temperature of 73F on the 20th tied the record high minimum temperature for July 20th previously set in 1977. The month was drier than average with a precipitation total of 3.09 inches, which was about a half inch less than the 120-year average and nearly an inch less than the 1981-2010 mean. Most of the monthly precipitation fell in a single storm, which totaled 2.03 inches in less than 24 hours on July 9th-10th. The calendar day total of 1.95 inches on the 10th surpassed the record for the date of 1.68 inches set in 1933. There were five thunderstorm days during the month, which is about average for July. The mean wind speed was 10.2 mph, which was the fourth lowest on record for July, and the prevailing direction was from the south. A peak gust of 35 mph from the south was observed on the 7th. July was much sunnier than average with 62 percent of the possible bright sunshine being observed, which is five percent above the long-term mean.