Climate datasets:

About Climate

A region’s climate is characterized by its usual weather conditions, seasons, and patterns in extreme weather events like heat waves, droughts, and hurricanes.

The world’s climate is shifting, becoming warmer with more precipitation and weather extremes. Over the past century in New York City, average temperatures have increased by 0.25°F per decade, precipitation by 0.72 inches per decade, and sea levels by 1.2 inches per decade. By the 2020s, a projected 25-30 days above 90°F are expected in a typical summer, resulting in more frequent and intense heat waves. Rainfall and precipitation are expected to increase by up to 5%, together with another 10 inches of sea level rise and increased probability of coastal storms with flooding (NYC Panel on Climate Change, Climate Risk Information, 2009).

Climate and Health

Even without long term changes in climate, New Yorkers face weather-related risks today. Heat and humidity cause serious illness and death every summer. In fact, more Americans die from heat waves in a typical year than all other natural disasters combined, both in direct mortality from heat stress (hyperthermia, also known as heat stroke) and by way of increases in the usual rates of deaths from natural causes due to the exacerbation of other medical conditions.

While less common, coastal storms also have imparted serious consequences throughout history and in recent years, most notably Hurricanes Katrina and Rita in 2005, from their devastating direct costs in over 1,800 lives along the Gulf Coast, to long-term mental health consequences among survivors. In 2011, Tropical Storm Irene caused extensive flooding throughout the Northeast and is estimated to be one of the costliest disasters in U.S. history, though New York City was largely spared.

The health impacts of weather events and climate change may be further compounded by power outages arising during heat waves and coastal storms. Such effects include gastrointestinal illness due to food spoilage, acute carbon monoxide poisoning from the use of generators, and illness and death among the medically frail due to mechanical equipment failure, lack of air conditioning, inability to obtain medical care, or extreme exertion (such as having to climb many flights of stairs due to elevator outages).

About the Data and Indicators

The Tracking Portal provides data on counts and rates of death, hospital admission, and treatment in an emergency department for heat stress. While these cases can be readily identified with hyperthermia listed as a diagnosis or cause of death, it is important to note that they reflect only a portion of the overall health impact of extreme heat. Increases in natural-cause hospitalization and death rates during heat waves (from cardiovascular disease, diabetes, and renal disease for example) may be estimated using statistical methods.


Air conditioning is the most important way to prevent heat stress and death on hot days.

  • Those most vulnerable to heat stress include older adults (>65 years) and people with health conditions including cardiovascular disease, diabetes, mental illness, or other cognitive impairment. Some medications can increase heat risk - talk to your doctor or pharmacist to learn more about medication-related risk and precautions to take during hot weather.
  • For air conditioners with a thermostat, a setting of 78°F is recommended to provide comfort while not wasting energy.
  • Check on those at-risk and assist them in staying cool and well hydrated. Seek medical attention immediately if the victim has a rapid heart rate, trouble breathing, is no longer sweating, displays very unusual behavior, or loses consciousness.

Being prepared is key to weathering hurricanes and coastal storms safely. 

  • Find out if you live in an evacuation zone, and stay tuned to TV and radio evacuation messages when a storm approaches. Information can be found at by searching “Hurricane Zones,” or by calling 311.
  • Have a “Go Bag” ready for evacuation, with copies of IDs and insurance cards, bottled water and non-perishable snacks, a list of medications and dosages, doctors’ phone numbers, a first aid kit, extra keys, a flashlight and battery operated radio, and small personal or family care items. .
  • Keep emergency supplies ready at home to shelter in place, if directed: a three-day supply of drinking water and non-perishable foods, first aid kit, flashlight, battery operated radio and extra batteries, whistle, iodine tablets or eyedropper and plain bleach (for disinfecting water if directed), and a battery-operated phone.

Key Messages

About 80% of heat stroke victims in New York City are overcome by excessively hot conditions in their own homes, as indoor temperatures in the urban environment may be even hotter than outdoor temperatures when an air conditioner is not available or not in use.

While heat-related mortality rates are overall substantially lower than in historical periods before electricity and air conditioning (a notorious heat wave in 1896 killed approximately 1,500 NYC residents), we may begin to see a reversal in this trend as a result of rising temperatures, depending on the extent of adaptation. In 2011, a Health Department survey estimated that 25% of New York City adults still do not have or rarely use air conditioning during hot summer weather, many of whom are at increased risk of heat stress due to age or poor health.

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