Northern and eastern Maine Monthly Climate Narrative:
July 2013 will be remembered as a month of extremes. A total of 7.27 inches of rain was observed at Caribou, making it the 2nd wettest July on record behind only 2011. The month began on a record dry pace with only 3 hundredths of an inch (0.03") during the first 16 days of the month. The dry month came to an abrupt end on the 17th when 3.81 inches of rain fell, mostly in heavy thunderstorms during a couple of hours in the afternoon. The 3.81 inches of rain that fell on the 17th was the 5th greatest calendar day rainfall ever observed at Caribou. At Bangor, monthly rainfall was much closer to normal with a total of 3.74 inches.
Across northern and eastern Maine precipitation ranged from 200-300 percent of normal in much of Washington and southeast Aroostook counties, with 150-200 percent across much of northeast Aroostook county. The highest rainfall total was observed at Baileyville in Washington County with 10.14 inches of rain. Across the remainder of the area rainfall was highly variable and ranged from as little as 50 percent of normal in parts of central Piscataquis County to 75 to 150 of normal across the remainder of northern and northwest Maine.
For the 2-month period of June through July a total of 13.33 inches of rain was observed at Caribou, which makes it the 2nd wettest summer so far behind only 2011. At Bangor, a total of 9.20 inches of rain was observed during the 2-month period which was nearly 3 inches above normal, mainly due to June 2013 being the 9th wettest on record.
The average temperature at Caribou this past July was 67.6 Degrees, which was 2 degrees above normal. At Bangor, the average temperature of 70.4 degrees was 1.9 degrees above normal. Temperatures across northern and eastern Maine ranged from 1.5 to 3 degrees above normal.
The high temperature at Caribou this past July of 94 degrees was observed on the 15th. This broke the previous record of 93 degrees for the date which was observed back in 1968. This was the warmest temperature observed at Caribou in 22 years, and was only 2 degrees shy of the all-time record at Caribou of 96. Weather records at Caribou only date back to 1939 and do not incorporate the entire decade of the 1930s. Many longer period stations such as Presque Isle had a high of 99 degrees during the summer of 1935. There were two consecutive days with a high temperature of 90 degrees of warmer, which had not occurred since the summer of 2010. On average, Caribou only observes one 90 degree day every other year.
At Bangor, the high temperature this past July was 92 degrees. There were 4 days with a high of 90 or warmer, which is 3 more than observed on average during the month of July.
After the heat broke around mid-month, temperatures were below normal much of the time the remainder of the month. The morning of the 22nd was very cool with lows in the 30s across the colder valleys in the north woods. Estcourt station observed a low of 33 degrees, and there may have even been a very light frost. During the hot weather around mid-month the highest unofficial Observation was 98 degrees 1 mile west of Marshfield.
The most significant weather occurred from July 17-20 when there were frequent thunderstorms, many of which were severe. There were 40 reports of wind damage, large hail, and flash flooding across northern and eastern Maine. The National Weather Service Forecast Office conducted a damage survey on the 18th, and confirmed that a weak EF-0 tornado briefly touched down 1 mile northwest of Danforth in Washington County.
Thunder was observed at Caribou on 3 days, which compares to an average of 7 days. At Bangor, thunder was observed on 6 days, which compares to an average of 2 days. The peak wind gust this past July at Caribou was 46 mph out of the north during a thunderstorm on the 17th. At Bangor, the peak wind gust of 41 mph was observed in a thunderstorm on the 19th.
The outlook for August from the Climate Prediction Center indicates that there are no strong climate signals that would tilt the odds toward an unusually hot or cool august. There are also no strong climate signals that point toward an unusually wet or dry August. The average temperatures begin to fall slowly during the month. At Caribou (Bangor) the average high falls from 76 (80) on the 1st to 71 (75) on the 31st. The average lows at Caribou (Bangor) fall from 55 (58) on the 1st to 50 (53) by the end of the month. The average August rainfall is 3.76 inches at Caribou and 2.98 inches at Bangor. The wettest August at Caribou was observed in 1981 with a total of 12.09 inches. The driest August was observed in 2002 with only 55 Hundredths of an inch of rain. At Bangor, the wettest August was observed in 2011 with a total of 8.32 inches. The driest August occurred in 1949 with only 61 hundredths of an inch. The days become shorter with a loss of nearly 1 1/2 hours of daylight during the month.