August 2018: Uncomfortably Hot and Humid

Posted: September 11, 2018, 11:56 am by chewitt

 As we close the books on meteorological summer (which ended on August 31st), probably the most memorable facet of August would not be flooding rains or record-breaking temperatures, but the extremely high levels of humidity. Many saw impressive streaks of seemingly never-ending oppressive dew points. Nonetheless, the Northeast did receive its fair share of rain and we did become immersed in a few heat waves. But what resulted from such a humid pattern? Let’s jump in.

Before getting into that, as should be the case late in the season, severe weather took a quieter turn… although the first week did not go without some gusty storms and four tornadoes. A warm front late on the 1st resulted in a spin-up rated an EF-0 in the College Point section of Queens in New York. This was then followed by a squall line that brought wind damage across the Hudson Valley on 3rd, only to be followed by two additional tornadoes! This time, the leftover boundary from the previous day spun a disturbance into New England on the 4th. One of the storms that passed through Dudley, MA resulted in a strong EF-1 that unfortunately injured at least one person. The other was an EF-0 near Woodstock, CT, which thankfully did not cause any serious damage or harm. 

Back to the humidity, we then embarked on a heat wave with temperatures reaching into the low 90s. The persistent southerly flow would continue to usher in downright intolerable, humid air. However, this was squashed a bit further south and enough energy was present to start the trend of afternoon thunderstorms along with a larger scale disturbance on the 11th. Heavy rains fell across Pennsylvania, New Jersey, and New York, parts of which saw over 2 inches of rainfall (including Hartford, CT and New York, NY).

The flip-flopping between high pressure and the occasional cold front would continue over the next two weeks, one resulting in a rather strong line of thunderstorms on the 17th that caused some wind damage. While the cold fronts brought some relief from the heat to parts of New England (temperatures dropping into the 70s), the Mid-Atlantic and much of Pennsylvania and New Jersey continued to warm well into the 80s. Another rainmaker would come late on the 21st into the 22nd bringing yet another bout of 1-2.5” rain amounts, especially across northern NJ and across the New York City metro.

As if we weren’t already familiar with the relentless high humidity at this point, to round out the month we entered a sweltering stretch of weather. A heat wave would send temperatures well into the 80s and 90s. While these didn’t break as many high temperature records as one would expect, parts of Massachusetts and New Hampshire smashed some, including Boston which hit 98 degrees on the 29th. More notable, however, were the overnight temperatures which resulted in some of the warmest nights on record. Almost every I-95 corridor city had done this, with uncomfortable low temperatures ranging between the upper 70s and low 80s. 


Record-breaking hours of dewpoints (highlighted in orange for 2018) at Washington-Dulles Airport

This was all thanks to the soupy air mass we had been stuck in, meaning that many areas simply struggled to cool off effectively. The humidity was indeed no joke. Many cities across the region recorded an anomalous number of hours where the dew point was at or greater than 70 degrees. Cities such as Albany, Hartford, and Portland all saw record breakers or challengers. Washington Dulles also recorded its most humid August on record, with nearly 1200 hours of 70 degree plus dew points for the warm season thus far! Check out the recent Washington Post article here further analyzing this. 

Link: "It's been relentless": Smothering Summer Heat in the Northeast (Washington Post)


Much of the Northeast ended up 3 to 6 degrees above normal for the month, which caused Boston to see its warmest August on record at 77.4 degrees (other cities like Hartford, CT were not far off in second place). Abundant rainfall carried over as well, with pretty much everyone outside of southern NJ and parts of the Delmarva Peninsula receiving their months’ worth or more (between 2 and 4 inch surpluses were the norm).  This helped continue to beat back a drought that began late spring which had been gradually encompassing New England.

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