May of 2018 was the wettest ever recorded for Maryland as the Statewide average of 7.68” surpassed the previous record of 7.31”. The month actually started off quite dry through most of the first half (except for a fairly wet 2-day event from Frederick County and westward), then the deluges began, especially pummeling the Ellicott City area (Howard County and parts of Baltimore County), again, after this area was so devastated back in July 2016. Many news stations and newspapers covered this so I won’t go further into it with this posting, though here is a nice WeatherTogether post from Kevin Shaw regarding the most-recent flooding event: Tremendous Flooding – Ellicott City – May 27, 2018 (and beyond) and also by the National Weather Service-Sterling (Baltimore/Washington): https://www.weather.gov/lwx/EllicottCityFlood2018.  Additionally, here is how this past month fits in historically.

 

The Top-10 Wettest Mays:

1. 7.68” (2018)

2. 7.31” (1989) (tie)

2. 7.31” (1948) (tie)

4. 6.93” (1990)

5. 6.86” (2008)

6. 6.65″ (1971)

7. 6.53″ (2003)

8. 6.48″ (1946)

9. 6.29″ (1924)

10. 6.02″ (1978)

 

Along with being Maryland’s wettest May it was also the third-warmest as the State Mean Temperature was 68.6°.

 

The Top-10 Warmest Mays:

1. 69.3° (2004)

2. 68.8° (1991)

3. 68.6° (2018)

4. 68.0° (1944)

5. 67.7° (2012)

6. 67.6° (2015)

7. 67.3° (1918)

8. 67.0° (1911) (tie)

8. 67.0° (1896) (tie)

10. 66.4° (1953)

 

The Baltimore Airport (BWI) recorded its 3rd wettest May with 8.17”, making it the 4th May since 2003 to make the top-10 wettest (dating back to 1871).

 

Baltimore’s Top-10 Wettest Mays:

1. 8.71” (1989)

2. 8.42” (2009)

3. 8.17” (2018)

4. 7.77” (2008)

5. 7.26” (1894)

6. 7.10” (1960)

7. 7.07” (1886)

8. 6.88” (1897)

9. 6.82” (1889)

10. 6.81” (2003)

 

The Airport also recorded its 5th-warmest May with a Mean Temperature of 69.6° (dating back to 1871):

 

Baltimore’s Top-10 Warmest Mays:

1. 70.8° (1880)

2. 70.6° (1991) (tie)

2. 70.6° (1944) (tie)

4. 69.8° (2004)

5. 69.6° (2018)

6. 69.4° (1911)

7. 69.3° (1918)

8. 69.1° (2015)

9. 69.0° (2012) (tie)

9. 69.0° (1942) (tie)

 

The National Weather Service Cooperative Observer Network ASOS station at the Maryland Science Center in Baltimore’s Inner Harbor measured 9.27″ in May 2018, just missing the all-time record for all stations that have existed, historically, within the city limits of Baltimore (BWI Airport is not included as it is located in Anne Arundel County). The all-time record is still the 9.31″ that fell at the Custom House in May 1989.

 

Data Source Note: Recently, the National Centers for Environmental Information revised historical climate data (especially older data prior to 1900), which may slightly affect some of the temperature data presented here. This is currently being investigated and any revisions will then be applied.

 

BALTIMORE STATION LOCATIONS  &  PERIODS OF RECORD
• South & Water Streets (SW Corner) – Fireman’s Insurance Bldg 12/23/1870 – 12/31/1888
• Holliday & E Baltimore Streets (SW Corner) – Neal Office Bldg 1/1/1889 – 5/31/1891
• W Monument St & Linden Ave (NW Corner) – Johns Hopkins University Physics Lab 6/1/1891 – 9/6/1895
• N Calvert & E Fayette Streets (SW Corner) – Equitable Building 9/7/1895 – 7/31/1896
• 532 N Howard Street – Johns Hopkins University Treasurer’s Bldg 8/1/1896 – 12/31/1907
• S Gay & Water Streets – Custom House 1/1/1908 – 7/31/1950
• Friendship/Baltimore-Washington International Thurgood Marshall (BWI) Airport 8/1/1950 – Present

 

Cover photo courtesy of ‘Livibility.com’