July Climatology

2018-08-04 19:09:40.000 – Adam Gill, Weather Observer/IT Specialist

 

As many people here in New England know, July was a very warm month across the Northeastern US. Mount Washington was no exception, though many sought refuge from the oppressive heat and humidity in the valleys since we are usually 20-30 degrees colder. We started off the month with a significant heat wave, nearly breaking our all-time record high of 72°F. We set record highs on the 1st (68°F), 4th (70°F), and the 5th (71°F). The last time the summit had seen 70°F was in 2006 and then 71 was the warmest temperature we have seen since we had last tied our all-time record high on June 26th, 2003.

So how does this July stack up to the other 86 that we have observed up here?

For temperature, this July was the second warmest that we have seen on record. The following table is the top 5 warmest summers we have seen as well as the 5 coldest on average. The average was made by adding the daily maximum and minimum and dividing by 2. The daily maximum and minimum are reported at midnight.

Top 5 Warmest July’s

Rank

Year

Average Temp.

1st

1955

53.5

2nd

2018

53.1

3rd

2013

53.1

4th

2006

52.8

5th

1952

52.6

Top 5 Coldest July’s

Rank

Year

Average Temp.

86th

1962

44.3

85th

1992

44.7

84th

1956

44.8

83rd

1954

44.9

82nd

2000

45.1

One of the reasons that we saw such warm temperatures is because there was a large ridge that was centered over much of the eastern US. This allowed for warm, tropical air masses to flow into New England making it feel more like Florida in the valleys. The building can get uncomfortably hot during once the temperature starts to get into the 60’s and there is no wind. With all the State Park concession ovens going plus all the people up visiting can make for a warm stagnant air inside.

Now lets take a look at precipitation. We started off the month with a drought and much of the initial precipitation was from thunderstorms, which don’t always help in a drought. The reason is that rainfall rates are so high, much of the precipitation runs off into streams rather than replenishing ground water. The last few weeks of July saw much more in the way of frequent rain showers over multiple days which ended up helping relieve some of the drought here in New England but not all of it. We ended up with 9.11 inches of rain which was 0.34 inches above average which is 8.77 inches.

Wettest July’s

Rank

Year

Precipitation (in.)

1st

1996

16.85

2nd

1969

15.53

3rd

1997

15.46

4th

2009

12.99

5th

2008

12.88

22nd

2018

9.11

Driest July’s

Rank

Year

Precipitation (in.)

86th

1955

2.69

85th

1948

3.28

84th

2011

3.63

83rd

1959

3.67

82nd

1978

3.75

Finally we will look at winds! With the ridge over us for much of the month, the overall average wind was fairly low but with a thunderstorm early in the month along with a strong cold front after the heat wave, we hit 95 mph twice. Getting to 90 does not happen every July but having it happen twice or more has only occurred 14 times in our history. Here is a look at our windiest July’s and what place this year got.

Windiest July’s

Rank

Year

Wind Speed Avg.

1st

1983

32.8

2nd

1977

31.7

3rd

1935

30.5

4th

1997

29.9

5th

1971

29.8

52nd

2018

24.5

So far this August has started off well above average again and looking into the first half of the month, it is looking like this trend will continue. The weather pattern is also conducive to frequent muggy days as well as continued showers and thunderstorms.

 

Adam Gill, Weather Observer/IT Specialist

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