October’s Surprising Weather

Roosevelt Island is Beautiful in the Fall

Washington, D.C.’s warmest October temperature on record was 96 degrees (on October 5, 1941).  However, this fall it hasn’t been 90 degrees since September 9 when it was 94.   In fact, the warmest temperature this month in the Nation’s Capital was 79 degrees on October 9.  The coolest temperature so far this month occurred on October 19 when the low fell to 37 degrees.  However, temperatures fell to the upper 20s the very same morning.

The warmest October on record in the Nation’s Capital was in 2007 when the average monthly temperature (combining daily highs and lows) was 67.1 degrees, compared to a monthly average of 59.5 degrees.  The coolest October on record in the Nation’s Capital came in 1876 when the average temperature was 50.7 degrees.  Modern weather observations in Washington, D.C. have been made at National Airport since it opened in 1941.

Meteorological fall runs from September 1 through November 30.  Meteorologists break up the seasons into equal three-month periods for the ease of averaging climate data.  This fall got off to a torrid start in the Nation’s Capital, with seven of the first ten days of September seeing high temperatures in the 90s.  Although September was nearly four degrees warmer than average in Washington, D.C., the pendulum has swung the other way in October.  So far this month, there have been five days with highs in the 50s in the Nation’s Capital, which is more characteristic of the second half of November.  Through October 26, this month has been a full degree cooler than average in Washington, D.C.

Last week, Hurricane Patricia became the strongest hurricane on record in the Western Hemisphere.  That’s typical of an El Nino year when conditions are favorable for more frequent and more intense hurricanes in the Eastern Pacific Ocean.  The remnants of Hurricane Patricia will enhance the rainfall across the Mid-Atlantic Region tonight and tomorrow.  However, no high winds or flooding rains are expected.

The Mid-Atlantic Region has felt the impacts of former tropical storms and hurricanes in October several times.  In October 1995, the remnants of Hurricane Opal brought appreciable rainfall and a few tornadoes to the Maryland suburbs of Washington, D.C.  Just three years ago, the Mid-Atlantic Region felt the frightening impact of Sandy.  At one point, Sandy was a major Category 3 hurricane while over the open ocean, but weakened before coming ashore.  The DC Metro Region saw record rainfall from Sandy as 3.85” of rain fell on October 29, 2012.  Fortunately, rainfall totals like that aren’t expected from the remnants of Patricia.