August was the fourth wettest August on record, but until 8/21 the month had been a dry one, with rainfall 50% below average. Then, Hurricane Henri produced 8.19" of rain over three days (Aug. 21-23), accounting for nearly 80% of August's 10.32" of rain. (The other 28 days of the month had just 2.13".) This was the second month in a row with more than ten inches of rain (July had 11.09", making it the third wettest July), just the second time this has happened (however, the first time, in March and April 1983, is disputed since the rain gauge in Central Park wasn't functioning properly for much of the year). Although August's rainfall was less than an inch below that of July, its number of days of measurable precipitation was half as many (nine vs. eighteen).
One out of four Augusts have been warmer than July, and August 2021 was one of them (77.5° vs. 76.0°). The month was 1.4 degrees above average, making it the City's 17th hottest August (out of 153). However, there was a disparity in rankings of the average high and low, as only five other Augusts have had a warmer average low than this August (2.2 degrees warmer than average), but the average high (just 0.6 above average) was ranked much lower, at #39. This difference in rankings wasn't unique to this August, as the trend during the 2000s has been for overnight temperatures to be more above average than daytime readings (one of the effects of global warming).
After the first five days of the month were five degrees below average, the rest of the month was three above average (with only five of the 26 days having cooler than average mean temperatures). August had five readings in the 90s, one more than July, and it had five more days than July with lows of 75° or warmer. August's days in the 90s were comprised of back-to-back days on Aug. 12-13, and a three-day heat wave two days after Henri's departure (Aug. 25-27). The month's hottest reading was 94° on 8/13.
Finally, this was the eighth year in a row in which August had no readings in the 50s. The coolest temperature was 63° on 8/2. (Meanwhile, July's streak of 12 years with no lows cooler than 60° was broken this year).
Here are monthly recaps for past Augusts: