Heat waves are one of the leading weather-related causes of death in the Unites States. Recognizing the current and future extreme heat risk to its population, New York City decided to assess climate risk and vulnerability. To assess the risk of future extreme heat events, the New York City Panel on Climate Change used the most up-to-date global climate models at the time. The Panel's Climate Risk Information Report identified a baseline, covering the period 1970-2000, of two heat waves per year on average. New York City projected the number of heat waves could increase, using the 90th percentile as the high estimate, to seven per year by 2050. Additionally, the Panel's 2013 report states the average annual number of days over 90°F could more than triple, under the high estimate, from 18 to 57 by 2050.
New York City updated its emergency response and hazard mitigation plans as a result of its Climate Risk Information Report. New York City is continuing to refine their climate projections to better assess climate vulnerability under the best-available science. The most recent update was in the 2015 New York City Panel on Climate Change: Building the Knowledge Base for Climate Resiliency Report, which for the first time included projections to the year 2100.