Baltimore’s Weather Review of 2018
Precipitation was the name of the game in 2018. Baltimore set many records, including the greatest all-time calendar-year total with 71.82″ at Baltimore/Washington International Thurgood Marshall Airport (BWI). This is most impressive considering official precipitation records began in downtown Baltimore back in 1871 (official records were shifted to the airport in August 1950) so this is the highest annual total in the last 147 years! If we were to include the pre-National Weather Service data recorded from 1817-1870 (from various observers of which I cannot vouch for the accuracy), the year 2018 still surpasses all of those years, subsequently making it the wettest annual amount in over 200 years! Oddly enough, 2018 started off quite dry as January saw only 1.00″ the entire month, the 6th driest January since 1871 (which followed the 8th driest December to end 2017). February was unusually wet, March was considerably drier than Normal, then April was almost exactly average. However, May is when the floodgates opened through much of the rest of the year. Amazingly, 5 different months of 2018 recorded a top-10 ranking as wettest of all-time, including July and November each reaching their #1 wettest. For how each month in 2018 stacked up, compared to the 30-Year Normal period 1981-2010, see the table below.
The Maryland Science Center, in downtown Baltimore’s Inner Harbor, recorded 68.76” which breaks the record for all historical official weather stations within the Baltimore city limits (BWI Airport is located in Anne Arundel County, just south of Baltimore, so is not included), the previous record being 66.38” inches at Ft. McHenry in 1889.
Baltimore City Limits: Record Precipitation – Daily, Monthly, Annual Amounts
Depending on my availability, I might be adding more features and data to this post in the near future. If you notice any issues with the data, please let me know and I’ll look into revising the information.
Cover photo: Federal Hill rowhouses courtesy of Zumper
MONTHLY AND ANNUAL PRECIPITATION IN 2018
Baltimore Airport (BWI)
(amounts in inches)
| Period | Precip. Total | Percent of 30-Year Normal | Notes/Top-10 Rankings |
| January | 1.00″ | 33% of the Normal of 3.05″ | #6 driest January (driest being 0.29″ in 1955 |
| February | 5.30″ | 183% of the Normal of 2.90″ | |
| March | 2.25″ | 58% of the Normal of 3.90″ | |
| April | 3.20″ | 100% of the Normal of 3.19″ | |
| May | 8.17″ | 205% of the Normal of 3.99″ | #2 wettest May of all-time (only behind 8.71″ in 1989) |
| June | 4.77″ | 138% of the Normal of 3.46″ | |
| July | 16.73″ | 411% of the Normal of 4.07″ |
|
| August | 3.84″ | 117% of the Normal of 3.29″ | |
| September | 9.19″ | 228% of the Normal of 4.03″ | #6 wettest September (wettest being 13.32″ in 2011) |
| October | 2.69″ | 81% of the Normal of 3.33″ | |
| November | 8.14″ | 247% of the Normal of 3.30″ | #1 wettest November (previous record 7.68″ in 1952, an increase of 6.0%) |
| December | 6.54″ | 194% of the Normal of 3.37″ | #7 wettest December (wettest being 8.06” in 2009) |
| Year 2018 | 71.82″ | 171% of the Normal of 41.88″ | #1 wettest Calendar Year (previous record 62.66″ in 2003, an increase of 14.6%) |
OTHER PRECIPITATION FEATURES IN 2018
Calendar-Day Records
| Date | Amount | Notes/Top-10 Rankings |
| July 17 | 3.35″ | Previous record for the date: 2.25″in 1947 |
| July 21 | 4.79″ |
|
| July 24 | 4.07″ |
|
| Sept 9 | 2.23″ | Previous record for the date: 1.35″ in 1950 |
| Sept 18 | 2.22″ | Previous record for the date: 2.13″ in 2003 |
| Dec 15 | 2.24″ |
|
24-Hour Records
| Ending Date | Amount | Top-10 Rankings |
| July 17 | 4.04″ | #6 all-time July 24-Hr record |
| July 21 | 4.79″ | #2 all-time July 24-Hr record |
| July 24 | 4.07″ | #5 all-time July 24-Hr record |
| Dec 16 | 2.52″ | #7 all-time December 24-Hr record |
2-Day Records
| Ending Date | Amount | Top-10 Rankings |
| May 16 | 2.96″ | #6 all-time May 2-Day record |
| July 22 | 5.29″ | #3 all-time July 2-Day record |
| July 24 | 5.49″ | #2 all-time July 2-Day record |
| July 25 | 4.46″ | #7 all-time July 2-Day record |
| Dec 16 | 2.93″ | #7 all-time December 2-Day record |
Number of Monthly Amounts
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|
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Number of Days of Measurable Precipitation
| Amount | Number of Days | Notes/Top-10 Rankings | |||||
| ≥4.00″ | 2 | #1 all-time | |||||
| ≥3.00″ | 3 | #1 all-time, tying 2011, 1952, 1944, and 1889 | |||||
| ≥2.00″ | 6 | #1 all-time, tying 1952 and 1889 | |||||
| ≥1.00″ | 20 | #1 all-time, tying 1979 | |||||
| ≥0.50″ | 48 | #1 all-time | |||||
| ≥0.25″ | 72 | #2 all-time, behind #1’s 76 days in 2003 | |||||
| ≥0.01″ | 145 | #7 all-time, tying 1883 and 1884, well-behind #1’s 169 days in 1889 |
TEMPERATURES
(in degrees Fahrenheit)
Overall the year averaged 56.7°, which was 1.6° above the 30-Year Normal (1981-2010). The months with the warmest departures were February (tying for 10th warmest February of all-time), May, and September, all of which were more than 5 degrees above Normal. The coolest departures were March and November, -3.4° and -2.9° respectively. January and April were the only other below-normal months in the year.
As has been the case for quite some time, above-Normal departures in 2018 were more extreme with the Minimum Temperatures. The Average Maximum of 65.9° was 0.8° warmer than the Normal of 65.1° while the Average Minimum of 47.5° was 2.4° warmer than the Normal of 45.1°.
Average Monthly, Annual, and Seasonal Temperatures
| Period | Average Maximum | Average Minimum | Mean | Mean Normal | Mean Departure |
| January | 42.1° | 21.9° | 32.0° | 32.9° | -0.9° |
| February | 51.2° | 32.5° | 41.8° | 35.8° | 6.0° |
| March | 49.2° | 31.3° | 40.2° | 43.6° | -3.4° |
| April | 62.8° | 41.3° | 52.1° | 53.7° | -1.6° |
| May | 79.5° | 59.7° | 69.6° | 62.9° | 6.7° |
| June | 82.5° | 62.6° | 72.6° | 72.4° | 0.2° |
| July | 87.7° | 67.9° | 77.8° | 77.0° | 0.8° |
| August | 87.7° | 69.2° | 78.4° | 75.1° | 3.3° |
| September | 80.0° | 66.0° | 73.0° | 67.8° | 5.2° |
| October | 68.3° | 50.3° | 59.3° | 56.1° | 3.2° |
| November | 51.3° | 35.9° | 43.6° | 46.5° | -2.9° |
| December | 48.1° | 31.3° | 39.7° | 36.7° | 3.0° |
| Annual | 65.9° | 47.5° | 56.7° | 55.1° | 1.6° |
| Winter | 45.9° | 27.0° | 36.4° | ||
| Spring | 63.8° | 44.1° | 54.0° | ||
| Summer | 86.0° | 66.6° | 76.3° | ||
| Autumn | 66.5° | 50.7° | 58.6° |
Monthly and Annual Extreme Temperatures for 2018
| Period | Period Maximum | Date | Period Minimum | Date |
| January | 64° | 23rd | 1° | 7th |
| February | 79° | 21st | 12° | 3rd |
| March | 75° | 30th | 23° | 11th |
| April | 87° | 13th | 31° | 11th |
| May | 92° | 3rd | 42° | 1st |
| June | 96° | 30th | 50° | 12th |
| July | 99° | 3rd | 56° | 9th |
| August | 96° | 29th | 56° | 24th |
| September | 95° | 6th | 54° | 30th |
| October | 88° | 4th | 32° | 25th |
| November | 75° | 1st | 24° | 23rd |
| December | 63° | 21st | 19° | 8th |
| Annual | 99° | 7/3 | 1° | 1/7 |
Number of Days Reaching Specific Temperature Thresholds
| Period | Max Temp ≥90° | Max Temp ≤32° | Min Temp ≤32° |
| January | 0 | 9 | 25 |
| February | 0 | 0 | 15 |
| March | 0 | 0 | 24 |
| April | 0 | 0 | 5 |
| May | 5 | 0 | 0 |
| June | 5 | 0 | 0 |
| July | 12 | 0 | 0 |
| August | 12 | 0 | 0 |
| September | 5 | 0 | 0 |
| October | 0 | 0 | 2 |
| November | 0 | 0 | 13 |
| December | 0 | 0 | 19 |
| Annual | 39 | 9 | 103 |
| The number of days in 2018 with Minimum Temperatures ≤32° was 103, tying for 17th place with several years for highest amount since 1871, the highest being 116 days in 1966 and 1962 |
High Maximum Temperature Records
| Date | Temperature | Notes/Top-10 Rankings |
| February 20 | 76° | Tying previous record for the date: 76° in 1930 |
| February 21 | 79° |
|
| May 2 | 90° | Previous record for the date: 88° in 1951, 1930, and 1913 |
| May 3 | 92° | Previous record for the date: 91° in 1913 |
| May 4 | 91° | Previous record for the date: 90° in 2001 |
Low Minimum Temperature Records
| Date | Amount | Notes |
| January 7 | 1° | Baltimore hasn’t reached 0° since Feb. 5, 1996 (reaching 1° twice since), the longest period in its history. |
Low Maximum Temperature Records
| Not a single Low Maximum Temperature record was set in 2018 |
High Minimum Temperature Records
| Date | Amount | Notes/Top-10 Rankings |
| January 12 | 53° |
|
| February 21 | 52° | Previous record for the date: 49° in 1981 |
| April 13 | 63° | Previous record for the date: 57° in 1977 |
| April 14 | 65° | Previous record for the date: 62° in 2014 and 1896 |
| October 10 | 69° | Tying previous record for the date: 69° in 1939 and 1879 |
| October 11 | 69° | Previous record for the date: 68° in 1990 |
| December 15 | 48° | Previous record for the date: 46° in 1891 |
Top-10 Monthly Mean Temperature Extremes
| Month | Mean Temp. | Notes/Top-10 Rankings | |||||
| February | 41.8° | #10 warmest, tying 1939, the warmest being 44.2° in 2017 | |||||
| May | 69.6° | #5 warmest, the warmest being 70.9° in 1880 | |||||
| September | 73.0° | #10 warmest, tying 1933, the warmest being 77.5° in 1881 | |||||
| Not a single Top-10 Coldest Monthly Mean Temperature was set in 2018. |
SNOW
(Amounts in Inches)
It was a below-Normal Calendar Year as only 12.8″ fell, just 63% of the Normal of 20.2″. March accounted for more than half of the annual total.
The number of days with snowfall ≥1.0″ was 5 (1 each in January, February, and November, and 2 days in March).
There were 8 days with snowfall ≥0.1″ (2 days in January, 1 each in February and November, and 4 in March).
The greatest depth of snow was 4″ on March 22nd
There was a total of 7 days with snowcover ≥1.0″ (4 in January, 1 in February, and 2 in March). Note that snow depth is measured at 0700 Hrs local time so there could be more than an inch of accumulation on a day but it may have melted by the time the next observation was taken.
Monthly and Annual Snowfall
| Period | 2018 Snowfall (in inches) | 30-Year Normal | Departure from Normal in inches |
| January | 2.2″ | 6.8″ | -4.6″ |
| February | 2.2″ | 8.0″ | -5.8″ |
| March | 6.7″ | 1.9″ | 4.8 |
| April | 0.0″ | T | 0.0″ |
| May | 0.0″ | 0.0″ | 0.0″ |
| June | 0.0″ | 0.0″ | 0.0″ |
| July | 0.0″ | 0.0″ | 0.0″ |
| August | 0.0″ | 0.0″ | 0.0″ |
| September | 0.0″ | 0.0″ | 0.0″ |
| October | 0.0″ | T | 0.0″ |
| November | 1.7″ | 0.4″ | 1.3″ |
| December | 0.0″ | 3.1″ | -3.1″ |
| Annual | 12.8″ | 20.2″ | -7.4″ |
Daily Snowfall Records
| Date | Amount | Notes | |||||
| Nov. 15 | 1.7″ | Previous record 1.2″ in 1908 | |||||
| Nov. 16 | Trace | Tying the record of a Trace also in 2000, 1980, and 1940 | |||||
Data Source:
- National Weather Service Forecast Office – Baltimore/Washington (Sterling, VA): https://w2.weather.gov/climate/index.php?wfo=lwx
- Applied Climate Information System (ACIS): http://scacis.rcc-acis.org/