New York City's Summers (1822-68)

[donsutherland1]

At 8:57 PM EDT, the sun will cross the Equator and summer will officially begin in the Northern Hemisphere.

While one looks ahead to what will likely be a warmer than normal summer with some periods of high heat, it is a good time to look back to some of the earlier hottest days prior to regular recordkeeping in New York City.

During the 1825-1868 period, there were 17 occasions on which the temperature rose to 100° or above in New York City. The earliest such reading occurred on June 21, 1825 when the mercury topped out at 100°. The latest occurrence was August 6, 1838 when the thermometer bubbled over at 101°.

The highest readings for June, July, and August were as follows:


June:
103°, June 30, 1855 (all-time monthly high)

July:
103°, July 10, 1838

August:
101°, August 5, 1835 and August 6, 1838

Summer 1838 saw 4 100° readings and had a mean temperature of 75.0°, making it the 4th warmest in the 1822-68 period. One has to bear in mind that New York City was far less urbanized and more susceptible to radiational cooling than it is today.

Summer 1825 was the warmest on record with a mean temperature of 76.6°. If one included modern records, Summer 1825 would be tied for 6th warmest with Summers 1980 and 1988.

Perhaps most remarkable of all, July 1825 had a monthly mean temperature of 81.3° in spite of NYC's less urbanized state. Only July 1999 (81.4°) was warmer.

In terms of cool summers, Summers 1836, 1837, and 1839 were all cooler than Summer 1903 (mean: 69.3°), which ranks as the coolest summer since regular recordkeeping began in 1869. This development likely reflects, at least in part, the less urbanized state of the city.

Coolest Early Summers:

1837 67.5°
1836 67.7°
1839 69.1°