Because, you know, there's nothing better to do on the first nice day in a decade than to research the history of the word "nor'easter," I went out and found the following:
... Fithian kept a diary. The entry for Thursday, August 25, 1774, reads: "Still stormy. The gentlemen who are sailing up the Bay [presumably the Chesapeake Bay] to the Congress have a disagreeable time. This is a true August northeaster, as we call it in Cohansie [Virginia]."
The contraction of "northeaster" to "nor'easter" occurred much later, between 1836 and 1848. Referring to a sailing ship, B. D. Walsh wrote, "Slack your sheets. A strong nor'easter's groaning." ...