Weather Quiz

The White House, Washington, D.C.

True or False.  August 2018 is poised to finish as a warmer and wetter than average month in the Nation’s Capital for the first time since 2011.

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Answer to the August 17 Weather Quiz question.

True.  Washington, D.C.’s all-time hottest temperature on record is 106°.  It has been 105° a handful of times as well, most recently on July 7, 2012.

Hurricane Ophelia, October 2017      Source: NOAA

September is commonly the most active month of the hurricane season in the Atlantic Ocean Basin, which includes the Gulf of Mexico and Caribbean Sea.  The tropics often get busier as the month of August wears on and conditions get more favorable for tropical development.  However, that hasn’t been the case in 2018 and there hasn’t been an Atlantic hurricane since Chris dissipated on July 12.

The month of August has been very quiet in the Atlantic Ocean this season with only two weak and short-lived tropical storms.  There have been three prior Augusts since 2000 with no hurricanes, according to NOAA records, with the most recent being in 2013.  This illustrates that while uncommon, it’s not unheard of for the Atlantic Ocean to go without a hurricane in August.  An average hurricane season in the Atlantic has 12 tropical storms, of which 6 becomes hurricanes and 3 of those become “major” Category 3/+ storms.

The 2013 Atlantic hurricane season was quieter than average with 14 tropical storms and only 2 minimal hurricanes, but none in August.  While the 2001 Atlantic hurricane season was busier than average, none of the three Atlantic tropical storms in August 2001 became hurricanes.  Likewise, August 2002 was a relatively quiet month with only two tropical storms but September 2002 was quite active with seven tropical storms and three hurricanes.

 

These examples illustrate that a hurricane season can be busier than average, overall, despite having a quiet August.  Also, having a quiet month of August in the tropical Atlantic does not in any way foreshadow a quieter than average September, traditionally the busiest month of the hurricane season.  There have been a number of times where an otherwise active season had a slow stretch of weather in the tropics.  According to a tweet from hurricane expert Dr. Philip Klotzbach, of Colorado State University, “…1961 had zero Atlantic named storms in August. September 1961 was very active with four major #hurricanes forming.” 

 

The 2018 Atlantic hurricane season is far from over, despite the relatively quiet last six weeks.  It’s important to remember that it only takes one storm to make it a damaging and/or deadly hurricane season.  For example, only one major hurricane formed in 1992, but that was catastrophic Hurricane Andrew.  The strongest Atlantic storm so far this year was Category 2 Hurricane Chris.  No major hurricane has developed in the Atlantic Ocean since Hurricane Ophelia last October.

Late August Heat Envelops DC

Although DC’s average daily high temperatures fall to the mid-80s by late August, there have been occasional stretches of very hot weather.  Record high temperatures are still in the upper 90s and occasionally touch 100° into early September.  However, the frequency which triple-digit heat occurs in DC drops precipitously by this time of year as compared to late-June to mid-August. 

The next few days are going to be very hot and humid in the DC Metro Area.  Although no record highs are likely downtown, the combination of increasing relative humidity with high temperatures in the low-to-mid 90s will make it feel very uncomfortable.  That’s especially true after the recent fall-like weather when temperatures have been below average on five of the last eight days since DC’s last heat wave ended August 18.  A “heat wave” is defined as a minimum of three consecutive days with high temperatures of at least 90°.

DC residents will be able to compare this week’s heat wave to a similar week just two years ago.  High temperatures were in the low-to-mid 90s from August 26 – August 31, 2016.  No record high temperatures were challenged, but this six-day heat wave helped secure August 2016’s place as DC’s second hottest August on record with a monthly average temperature of 82.7° (combining daily high and low temperatures) far above the monthly average of 78.1°.

August 1998 was also a warmer than average (79.4°) month in Washington, D.C. and finished with an even more impressive streak of hot weather.  From August 22 through August 31, high temperatures in DC were in the 90s on all but one day.  A record-tying high temperature of 97° occurred on August 25, 1998.  Meanwhile, August 1993 also finished with significantly above average temperatures.  From August 25 through September 3, 1993, high temperatures were in the low-to-mid 90s.

August 2018 has been a wetter than average month with 4.85” of rain through August 26.  This month will also finish as a warmer than average month with average temperatures 1.9° warmer than average through August 26.  The last time Washingtonians had an August that finished both warmer and wetter than average was in 2011.

Record High Temperatures (Source: NOAA)

August 28

Washington, D.C., National Airport (DCA): 99° (1948)
Dulles International Airport, Sterling, VA (IAD): 98° (1993)
Baltimore, MD (BWI Airport): 101° (1948)

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August 29

DCA: 98° (1973, 1953)
IAD: 98° (1991)
BWI: 100° (1953)

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August 30

DCA: 99° (1953)
IAD: 99° (1991)
BWI: 101° (1953)