In a typical year, about two-thirds of New York's days in the 90s/100s occur before Aug. 1. Since 1900 there have been 21 years that were significantly "front-loaded", including the recent years of 2011, 2012 and 2013 (see chart below). And there have been eight years in which no 90-degree temperatures occurred on Aug. 1 or later. The last time this happened was in 1986. Meanwhile, the fewest number of days in the 90s before Aug. 1 is one, which occurred in 2004, 1960 and 1902. And once every seven years the post-Aug. 1 period has had the most 90-degree days (2015 was the most recent of those years). The two biggest "back-loaded" years were in 1970 when there were seven 90-degree days before Aug. 1 and fifteen in Aug./Sept., and 2015, with six before and fourteen after.
The following two charts show the most "front loaded" and most "back loaded" years since 1900, arranged in descending chronological order.
1991 had the most days in the 90s before Aug. 1, twenty-seven, followed closely by 1993 and 1966, both which had twenty-six. 1980 had the most 90-degree days to occur on Aug. 1 or later, eighteen. This was four more than the number of 90-degree days before Aug. 1 of that year. (Both amounts were above average.)
|Most 90-Deg Days Before Aug. 1|
|Year||August 1||and Later|
|Most 90-Degree Days After Aug 1|
|Year||and Later||August 1|
(Many thanks to Eugene Demarco who's spreadsheet showing year-by-year dates of 90-degree highs made this analysis so much easier to do.)