Precipitation
Key Finding: New York State has experienced increases in total precipitation and heavy precipitation events, and these trends will continue through the end of this century. Heavy rainstorms that lead to flooding are projected to become more frequent across the state. Precipitation is expected to increase the most in winter. Lake-effect snowfall is projected to increase over the next few decades, but as temperatures continue to rise, more winter precipitation near the Great Lakes will fall as rain. Elsewhere in the state, snowfall and snowpack are likely to decrease with warmer winter temperatures.
Climate Projections and Our Actions
Projections of future climate change depend on the world’s future emissions of heat-trapping greenhouse gases. Some of the projections discussed here present a range of numbers, based on those future emissions. If global emissions are reduced, it would decrease future warming and some of the associated impacts, and the resulting climate changes could be closer to the lower numbers presented here—or even lower.
Total Annual Precipitation
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Rain and snow are key to sustaining life in New York State. Measuring total annual precipitation can show the amount of water available to meet the needs of ecosystems and people. It can also reveal the potential for excess precipitation and flooding. Annual precipitation is increasing statewide:
- Historical observations: From 1901 to 2022, total annual precipitation in New York State increased by 10% to 20%. Precipitation has also come to vary more widely from year to year.
- Projections for the future: Across New York State, total precipitation is projected to keep increasing by about 6% to 17% by the end of the century. The largest increases are projected for New York City, the Catskills, and the lower Hudson River Valley.
While New York is projected to remain a “water-rich” state, increases in total precipitation can affect water quality. For example, more precipitation can lead to more runoff—water that is not soaked up by the ground and runs off surfaces into water bodies. Runoff can contaminate water sources with pollutants, pathogens, and sediments.
State’s Changing Climate, to learn more about this figure. Source: Projections developed for this assessment.
Seasonal Precipitation
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Seasonal precipitation measures how much precipitation falls in winter, spring, summer, and fall. Seasonal precipitation is changing in New York State:
- Historical observations: Statewide, precipitation is fairly evenly distributed throughout the four seasons. In inland New York, precipitation is most intense in the summer. In coastal areas, precipitation is most intense during late spring and early fall. Over the past 100 years or so, fall precipitation increased the most. Spring and winter precipitation did not change significantly.
- Projections for the future: Winter and spring precipitation are projected to increase across New York State. Winter precipitation is projected to increase the most, increasing by 11% to 31% by the end of the century. Spring precipitation is projected to increase by 6% to 23% by the end of the century. Trends in summer and fall precipitation are less clear.
The timing of precipitation is key to certain parts of the economy, such as agriculture. For example, increases in spring rainfall make it difficult for farmers to get onto fields to plant their crops.
Heavy Precipitation
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Heavy precipitation refers to a large amount of rain or snow falling during a short period of time. This may occur in a single day or even a single hour. In New York State, heavy precipitation is increasing:
- Historical observations: Heavy precipitation events have happened more often since the 1950s in New York State. Across the state, storms previously considered “once-in-100-year” events have happened nearly twice as often as expected in recent years.
- Projections for the future: Extreme precipitation events are projected to happen more and more often across the state.
Heavy precipitation events can cause flooding and threaten agriculture, infrastructure, ecosystems, and communities. When one event happens soon after another, the impacts can be even worse. Heavy rain can damage crops and flood fields. Floods pose health risks like injuries, drowning, and illnesses from contaminated water. They can also damage homes, cause power outages, and block access to transportation and health care. People with fewer resources to prepare and recover are especially at risk.
Extreme and Annual Precipitation
While annual precipitation is generally increasing, it varies depending on the year. Extreme events often drive differences in annual precipitation from year to year. For example, the record for the most annual precipitation in New York State was set in 2011. This was largely because of the back-to-back extreme precipitation brought by Hurricane Irene and Tropical Storm Lee.
Snowfall and Snow Cover
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Whether precipitation falls as rain or snow matters for winter recreation, water supplies and streamflow, transportation impacts, ecosystems that depend on snow cover, and many more reasons. So does the length of time snow stays on the ground. A warmer climate generally means that more winter precipitation could fall as rain instead of snow, and snow will stay on the ground for a shorter amount of time. The snow season is changing in New York State:
- Historical observations: Snowfall trends vary across New York State. Long Island and New York City historically receive the least snow: an average of about 30 inches per year. Directly east of Lake Erie and Lake Ontario, total snowfall often reaches or exceeds 150 inches per year due to lake-effect storms (refer to text box).
“Lake-Effect” Snow
Lake-effect snow typically happens when the Great Lakes are not frozen. It is created by cold air moving across the warmer waters of the lake. As some of the lake water evaporates into the colder air, the air forms clouds that can produce heavy snow. Weather patterns in New York most often move from west to east, so the land east of large lakes tends to get the most lake-effect snow.
- Projections for the future: Climate models show a future with less snowfall, less snow cover and accumulation, and a shorter snow season. Lake-effect snow could increase in the next few decades as the Great Lakes get warmer and freeze less often. However, by later in this century, more of this precipitation will fall as rain instead of snow.
Snow-related recreation and tourism are key sources of jobs in the Adirondacks, Catskills, Central/Finger Lakes, and Great Lakes. However, as winters warm and the snow season shortens, some businesses such as ski resorts face difficulties or may be forced to close. Snow cover is also crucial for New York’s ecosystems. For example, less snow melting in the spring tends to result in lower water levels in streams and some wetlands, affecting the species that rely on them.
Explore Other Signs of Climate Change
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