The planet has warmed so much since those top 10 coolest El Niño onset summers of days past.    Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Jun 1 to Aug 17 Missing Count 1 1964-08-17 68.6 0 2 1965-08-17 68.