Notable June Tropical Storms and Hurricanes

"Chris" in 2012 was the last June hurricane in the Atlantic  (Source: NOAA)

Hurricane season in the Atlantic Ocean Basin runs from June 1 through November 30.  June and November are typically the quietest months of the season when atmospheric and environmental conditions are the least favorable for development.  That’s not to say there haven’t been a few high impact tropical storms and hurricanes during the month of June.  The Atlantic Ocean Basin includes the Gulf of Mexico and Caribbean Sea, areas more favorable for development early and late in the hurricane season.  

Allison (2001):  While it was only a tropical storm at peak intensity and when it made landfall in Texas, Allison achieved a dubious honor.  It was the first of only two Atlantic tropical storms to have had its name retired by the World Meteorological Organization.  Tropical storm and hurricane names are retired for being damaging and/or deadly (a la Katrina, Andrew or Michael).  What made Allison unique wasn’t its intensity, but its longevity.  After making landfall in Texas, its remnants lingered for days and caused devastating flooding.  Not until Hurricane Harvey in August 2017 did Texas residents see comparable flooding.

Agnes (1972):  Agnes became a minimal hurricane over the eastern Gulf of Mexico on June 18, but isn’t remembered for that.  As a weaker tropical storm, Agnes menaced much of the Mid-Atlantic and northeastern United States where its remnants caused widespread flooding.  Multiple June rainfall records were set from Virginia to New York, including DC’s wettest June day overall (6.11” on June 21, 1972).  Agnes subsequently had its name retired.

Alma (1966):  This was the last major Category 3 hurricane that developed in the Atlantic Basin during the month of June.  At peak intensity, Alma had sustained winds of 125 mph when it passed over the Florida Keys.  It weakened, however, as it tracked north and ultimately made landfall as a Category 1 hurricane in the Florida panhandle.  Had a similar storm occurred now, the impacts would be much more significant since Florida’s population and coastal development have both increased dramatically in the decades since Alma.

Audrey (1957):  Audrey remains the only Category 4 hurricane to impact the United States in June.  It made landfall near the Texas/Louisiana border with sustained winds of 145 mph and had devastating impacts both in coastal areas and well-inland.  According to NOAA, over 400 lives were lost, making it one of the deadlier US hurricanes on record. 

Hurricane intensity is ranked on the Saffir-Simpson Hurricane Wind Scale, with a Category 1 being a “minimal” hurricane with sustained winds speeds of 74 to 95 mph.  A hurricane becomes “major” when sustained winds reach 111/+ mph, making it a Category 3.  The strongest hurricanes are Category 5’s, with sustained winds of at least 157 mph. 

Recent June Weather Trends

Summer officially arrives in June and Washingtonians have experienced some of the hottest weather of the year over the course of the month.  June averages one 100° day roughly every five years in the Nation’s Capital.  Thirteen of the last 20 June’s have been warmer than average in Washington, D.C., following a period when 8 of 13 were cooler than average between 1992 and 2004.

June weather can be very streaky in the DC Metro Area.  June 1994 became DC’s hottest on record largely due to a 14-day heat wave with highs of at least 90° from June 13 – 26.  However, that was the longest heat wave of the 1994 summer with the hottest temperature during it being DC’s June 15 record high of 101°.  That would remain DC’s hottest temperature, overall, for more than three years until August 1997.

Fast forward 16 years to June 2010.  With 18 days of at least 90°, June 2010 supplanted 1994 as DC’s hottest June on record.  As many Washingtonians may recall, the summers of 2010, 2011 and 2012 were each exceptionally hot.  Triple-digit heat occurred in all three June’s, but not in the Nation’s Capital since 2012.

June is one of DC’s wetter months of the year, with a monthly average of 3.78” of rain.  Although June and July 2011 were each drier than average, August 2011 was significantly wetter than average.  That, in large part, was due to rainfall associated with Hurricane Irene.  It’s easy to get a significant amount of rain during the summer in the DC Metro Area because of current or former tropical systems.  June 1972 remains DC’s third wettest June due to the remnants of Hurricane Agnes. 

Despite recent strides, tropical systems are challenging to predict and any appreciable rainfall from one is atypical in this part of the country.  Therefore, Washingtonians shouldn’t expect any significant weather from a tropical system with any regularity in June.  Meanwhile, DC Area residents can see rainy summers much more frequently due to the position of the jet stream.  If the jet stream, a fast moving current of air in the atmosphere that helps steer weather systems, sets up in a particular way it can facilitate more frequent showers and thunderstorms. 

More typically, the dominant weather pattern in the Mid-Atlantic Region during the summer months is hazy, hot and humid weather with only isolated showers and thunderstorms.  That’s because the dominant weather feature for much of the eastern United States during the summer and early-fall is the “Bermuda High.”  That is a semi-permanent seasonal area of high pressure that pumps hot and humid air northward from the Deep South.  It also serves to suppress any widespread rainfall. 

June 2019 has gotten off to a relatively benign start in the Nation’s Capital with average temperatures through June 13 and a small rainfall surplus of 0.16”.  NOAA expects the next 8 to 14 days to be warmer and wetter than average in the DC Metro Area.  That means Washington, D.C. has a good chance to see its 10^th consecutive warmer than average June.

Does June’s Weather Predict the Rest of Summer ?

June is Washington, D.C.’s third hottest month of the year.  Area residents know there have been some significant June heat waves in recent decades, as well as some exceptionally wet weather.  However, June’s weather isn’t always a good harbinger of what the entire summer’s weather will be like.

One case in point occurred in June 1994.  Washingtonians experienced a 14-day heat wave with temperatures of at least 90° from June 13 – June 26.  The hottest day was the June 15^th record high of 101° that remains tied for third highest June temperature on record in the Nation’s Capital.  The month finished with an average temperature of 79.4°; significantly higher than DC’s June average of 75.2°.

The summer of 2016 was also interesting for DC residents in that the spring and first third of June were somewhat cool.  DC didn’t experience its first 90° day that year until June 11, several weeks after the average first 90° temperature normally occurs around May 18.  However, despite the relatively late first 90° of 2016, DC reached 100° on July 25, 2016 and on three more days the following month.  July and August 2016 each rank among the warmest on record in the Nation’s Capital.

The Nation’s Capital has experienced three of its five wettest Junes on record since 2006.  However, a wet or dry June isn’t a strong indicator of what might occur in July and August.  For example, Washington, D.C. had 14.02” in its wettest June on record in 2006, but was followed by below average July and August rainfall.  On the other hand, the month of June 2017 was DC’s third driest on record, but was followed by wetter than average conditions in July and August. 

While NOAA expects near average temperatures and rainfall this month, the Mid-Atlantic Region should expect a warmer and wetter than average summer, overall, based on NOAA’s three month outlook.

Washington, D.C.’s Five Warmest June’s (Source: National Weather Service)

1.  80.6° (2010)
2.  79.4° (1994)
3.  79.2° (1943)
4.  78.8° (2011)
5.  78.7° (1981)

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DC’s Five Coolest June’s

1.  65.9° (1907)
2.  67.0° (1903)
3.  68.6° (1927)
4.  69.1° (1926, 1878)

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DC’s Wettest June’s

1.  14.02” (2006)
2.  11.94” (2015)
3.  11.53” (1972)
4.  10.94” (1900)
5.  9.97” (2013)

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DC’s Driest June’s

0.86” (1940)
0.95” (1988)
1.13” (2017)
1.21” (1976)
1.24” (1954, 1894)

Weather Quiz

True or False.

June is the second hottest month of the year on average in Washington, D.C.

Severe Weather in June

United States Tornado Averages (Source: NOAA)

June is one of the most active severe weather months of the year in the United States.  June has the second highest average annual number of tornadoes (243), according to NOAA.  In addition to tornadoes, a thunderstorm is “severe” if it has hail 1” in diameter or greater, or wind gusts of at least 58 mph.  The DC Metro Area has had significant severe weather outbreaks in the last 15 years.

2016: An outbreak occurred on June 21, with multiple reports of large hail and damaging wind gusts.  Since anemometers (used to measure wind speed and direction) are relatively uncommon among the general public, reports of wind damage are often noted in severe reports absent wind speeds.  The concentration of the 193 “severe” wind reports on this day were in the DC Metro Area.  An EF-0 tornado also occurred in Howard County, Maryland.

2013: Two significant severe weather outbreaks occurred just days apart in the Mid-Atlantic Region.  Four tornadoes hit Maryland on June 10, while another six confirmed tornadoes occurred in the DC Metro Area on June 13.  One of the June 13 tornadoes was an EF-0 in Montgomery County, Maryland.  It was on the ground for more than 20 minutes, with a 21 mile track from North Potomac to Burtonsville.

2012: While June 2012 is often remembered for the highly destructive June 29 “derecho,” the DC Metro Area saw two other significant outbreaks earlier that month.  One occurred on June 1 with 38 tornadoes concentrated in the Mid-Atlantic Region.  Of these, Maryland had a state record of 10 tornadoes, which remains the highest state-wide single day total.  The strongest was an EF-1 in Harford County, with peak wind speeds of 86-110 mph. 

A few weeks later on June 22, the primary type of severe weather was damaging winds.  Two downbursts occurred in Maryland, one each in the towns of Bladensburg and Johnsville.  A downburst is an area of strong winds that occurs when cold air located high in the thunderstorm accelerates as it descends toward the ground.  These winds spread out as they reach the ground, where speeds can approach 100 mph.  That’s equivalent to the wind speeds in an EF-1 tornado.

2008: The severe weather on June 4 was one of the most widespread and destructive episodes in the DC Metro Area.  In the mid-afternoon a squall line passed through the DC Metro Area.  It produced a significant amount of damage, most notably widespread power outages that resulted from downed trees and power lines.  Four confirmed tornadoes also occurred, with one in Maryland and three in Virginia.

Unofficial Start of Summer

Last month was wetter and warmer than average in Washington, D.C.  It finished with 4.97” of rain (nearly an inch above average) and was also DC’s seventh warmest May, with an average temperature of 71° (5° above average).  Since April 2018, 14 of the last 16 months have been wetter than average in Washington, D.C.  In that time, the Nation’s Capital has accrued a rainfall surplus of 29.87”.

June, July and August make of “meteorological summer.”  On the other hand, astronomical summer doesn’t get underway until the summer solstice later this month.  Temperatures continue to rise throughout the month of June in the Nation’s Capital, going from average high and low temperatures of 80°/62° on June 1 to 88°/70° on June 30.  The hottest June temperature on record in Washington, D.C. occurred relatively recently when it was 104° on June 29, 2012.  That was also the last time 100° heat occurred in the Nation’s Capital during the month of June.  DC’s earliest 100° temperature was on June 5, 1925.  DC’s coolest June temperature on record is 43° (June 2, 1897).  

According to NOAA, 13 of the last 20 June’s have been warmer than average in Washington, D.C., including every June since 2010.  There have also been a total of 13 record high June temperatures in Washington, D.C. over the last 20 years.  That’s in addition to 21 record “high-low” temperatures.  In other words, on 21 occasions DC’s daily low temperature was at a record high level.  By comparison, there have only been two record “low-high” temperatures in the last 20 years and none since 2003.  That means that on two occasions daily high temperatures were much cooler than average.  Washingtonians haven’t had a record low temperature in June since 1979.

Washington, D.C. averages 3.78” of June rainfall, making it the second wettest of the year.  In the Nation’s Capital, 13 of the last 20 June’s have been wetter than average.  That includes three of DC’s five wettest June’s on record (2006, 2013 and 2015).  On the other hand, June 2017 was DC’s third driest with only 1.13”.  Decaying tropical systems have brought the DC Metro Area appreciable rainfall.  For example, June 1972 remains DC’s third wettest largely due to the impressive rainfall totals from remnants of Hurricane Agnes.  

NOAA currently expects an equal chance for above or below average temperatures and rainfall this month in the DC Metro Area.  That means Washingtonians can expect near average temperatures and precipitation this month.