Fall’s Midway Point

NOAA's Temperature Outlook for Late October

Significant weather events such as September’s record Mid-Atlantic heat wave followed by Hurricanes Matthew and Nicole have justifiably dominated weather headlines so far this fall.  There have been some other significant weather developments in the DC Metro Region that are worth discussing.  The Nation’s Capital has an ongoing rainfall deficit of 6.74” dating back to August 2015 (measured at National Airport).  The rainfall deficit at Dulles Airport in nearby Sterling, Virginia is 6.43” over the same period of time.

This deficit has developed since 11 of the last 14 months have been drier than average in the Nation’s Capital.  The record summer heat only served to acerbate the dry conditions across the Mid-Atlantic Region.  Although Washington, D.C.’s final 90-degree day of 2016 occurred on September 23, warmer than average temperatures have continued into October.  National Weather Service data shows temperatures over the first half of October (through October 15) have been 1.5 degrees warmer than average in the Nation’s Capital.

October is typically a highly variable weather month in the Mid-Atlantic Region.  The Nation’s Capital experienced October snowfall as recently as 2011 when a trace occurred at National Airport on October 29 with several inches in the northern and western suburbs.  Washingtonians experience 90-degree heat almost as infrequently in October with the last occurrence being in 2013. 

As Hurricanes Matthew and Nicole demonstrated earlier this month, October can feature impactful tropical systems.  The DC Metro Region was fortunate that neither storm had a direct impact on the region.  However, the Nation’s Capital could use a significant amount of rain to help offset the ongoing rainfall deficit.  The rainfall deficit is 2.29” at National Airport and 2.55” at Dulles Airport just since September 1.  That underscores the need for rain in the Mid-Atlantic Region.  However, no significant rain is expected during the next several days. 

To add to that, NOAA’s Climate Prediction Center indicates a 33% chance for above average temperatures during the next 8 – 14 days across much of the eastern United States.  That would enable October to finish as the 8^th warmer than average month of the year in the Nation’s Capital.  Not only are sunny and dry conditions expected for the next several days but a shift in the weather pattern will help temperatures warm to near record levels for the first half of the new work week.  My colleagues and I on the WUSA9 Weather Team will keep you posted.

Record Highs to Beat (in degrees Fahrenheit)

October 17

DCA: 86 (1938)
IAD: 83 (1963)
BWI: 90 (1938)

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October 18

DCA: 85 (1938)
IAD: 82 (2007)
BWI: 82 (1945)

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October 19

DCA: 88 (1938)
IAD: 83 (1991)
BWI: 82 (1947)

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October 20

DCA: 86 (1969)
IAD: 83 (1969)
BWI: 87 (1969)