The Weather on April 19, 1775: The Battle of Lexington and Concord

Contributed by Dr. William Minsinger, President Emeritus, BHOSC

Excerpt from a print by Amos Doolittle, The Battle of Lexington (1775).

America’s 250^th birthday – its semi-quincentennial – is a good opportunity to take a step back in time to look at the weather on April 19^th, 1775 during the pivotal Battle of Lexington and Concord. British General Thomas Gage in Boston had received intelligence that John Hancock and Sam Adams might be in Lexington and that four brass cannons that had been smuggled out of Boston (1), along with other munitions, were in Concord. Gage decided to dispatch troops, which set out in the early morning hours of the 19^th from Long Wharf in Boston to seize those supplies in Concord and perhaps capture the leaders of the rebellious colonials.

National Park Service map showing the route from Cambridge to Lexington and Concord and locations of major skirmishes and landmarks.

There has long been debate over the weather that day with some saying it was very warm or hot. However, David Ludlum – longtime editor of Weatherwise and AMS historian – wrote (2) that April 18^th saw rain showers during the day with clearing in the evening allowing Paul Revere a clear view of the two lanterns in the steeple of the Old North Church before he rode off to warn towns to the west. Revere was captured briefly at the Lincoln townline by advance British scouts. He had just met William Dawes and Dr. Samuel Prescott – who rode off to warn his hometown of Concord. Ludlum surmises that a cold front passed on the 18^th with Revere describing his ride as pleasant suggesting the temperatures were cool but not cold for the season. April 19^th dawned with clear skies and cool temperatures as the British troops arrived at Lexington Green and engaged colonial militia. Cumulus clouds built in the afternoon and yielded to a red sunset. The weather scenario may have led to some mud slowing the British march on dirt roads, but the April sun may have led to a warmer afternoon. However, the “heat” of the day may well have been more a reflection of the heat of the battle with the British suffering terribly as additional Minutemen companies engaged the British along the entire route of retreat from the battle at the Concord River bridge. The British slowly marched back toward Cambridge – reinforced by Lord Percy’s relief troops. The British suffered 247 casualties that day including 73 killed with another 53 missing, and the colonials had 88 casualties with 49 killed, which included eight under the command of Captian John Parker on Lexington Green. Parker’s men got their revenge later in the day as the British retreated from Concord back through Lexington.

Contemporary (1775) British map of Boston and troop movements during the Battle of Lexington and Concord. Note the reference to the “Bluehills”.

Print by Amos Doolittle, A View of the Town of Concord (1775) – note sky with cumulus clouds.

The best evidence of the cloud cover that day comes from the prints of Amos Doolittle – he was a silversmith and self-taught engraver from Connecticut who arrived with his New Haven militia company within two weeks of Lexington and Concord. He toured the battlefields and interviewed locals to create a series of four prints depicting the march and battles. Note the cumulus clouds and the trees fully leafed suggesting that early Spring 1775 in New England may have been milder than average. The relative warmth may have led to the idea that it was “hot” for the season, but the battle may well have been hotter than the actual air temperature on April 19^th. References

Bell, J.L., “The Road to Concord: How Four Stolen Cannon Ignited the Revolutionary War”, Westholme Publishing, 248 pp., 2016.
Ludlum, D. “Early American Winters, 1604-1820”, American Meteorological Society, 285 pp., 1966.