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 Climate Change Indicators: Snowfall
This indicator uses two different measures to show how
snowfall has changed in the contiguous 48 states.
Key Points
Total snowfall has decreased in many parts of the country
since widespread observations became available in 1930, with
57 percent of stations showing a decline (see Figure 1).
Among all of the stations shown, the average change is a
decrease of 0.19 percent per year.
In addition to changing the overall rate of precipitation,
climate change can lead to changes in the type of
precipitation. One reason for the decline in total snowfall
is because more winter precipitation is falling in the form
of rain instead of snow. Nearly 80 percent of the stations
across the contiguous 48 states have experienced a decrease
in the proportion of precipitation falling as snow (see
Figure 2).
Snowfall trends vary by region. The Pacific Northwest has
seen a decline in both total snowfall and the proportion of
precipitation falling as snow. Parts of the Midwest have
also experienced a decrease, particularly in terms of the
snow-to-precipitation ratio. A few regions have seen modest
increases, including some areas near the Great Lakes that
now receive more snow than in the past (see Figures 1 and
2). |
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Background
Snowfall is an important aspect of winter in much of the
United States. Many people depend on snow to provide water
when it melts in the spring—including 60 million people in
the western United States1—and many communities rely on snow
for winter recreation. Some plants and animals also depend
on snow and snowmelt for survival. The amount of snow that
falls in a particular area directly influences both snow
cover and snowpack, which refer to snow that accumulates on
the ground (see the Snow Cover indicator and the Snowpack
indicator).
Warmer temperatures cause more water to evaporate from the
land and oceans, which leads to more precipitation, larger
storms, and more variation in precipitation in some areas.
In general, a warmer climate causes more of this
precipitation to fall in the form of rain instead of snow.
Some places, however, could see more snowfall if
temperatures rise but still remain below the freezing point,
or if storm tracks change. Areas near large lakes might also
experience more snowfall as lakes remain unfrozen for longer
periods, allowing more water to evaporate. In contrast,
other areas might experience less snowfall as a result of
wintertime droughts.
Changes in the amount and timing of snowfall could affect
the spawning of fish in the spring and the amount of water
available for people to use in the spring and summer.
Changes in snowfall could also affect winter recreation
activities, like skiing, and the communities that rely on
these activities. |
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About the Indicator
This indicator tracks total snowfall as well as the
percentage of precipitation that falls in the form of snow
versus rain. These data were collected from hundreds of
weather stations across the contiguous 48 states.
Total snowfall is determined by the height of snow that
accumulates each day. These measured values commonly appear
in weather reports (for example, a storm that deposits 10
inches of snow). Figure 1 shows how snowfall accumulation
totals changed between 1930 and 2007 at more than 400
weather stations. These stations were selected because they
had high-quality data for this entire time period.
Figure 2 shows trends in the proportion of total
precipitation that falls in the form of snow during each
winter season. This is called the “snow-to-precipitation”
ratio, and it is based on comparing the amount of snowfall
with the total amount of precipitation (snow plus rain) in
each year. For this comparison, snow has been converted to
the equivalent amount of liquid water. These data are
available from 1949 to 2016.
Indicator Notes
Several factors make it difficult to measure snowfall
precisely. The snow accumulations shown in Figure 1 are
based on the use of measuring rods. This measurement method
is subject to human error, as well as the effects of wind
(drifting snow) and the surrounding environment (such as
tall trees). Similarly, snow gauges for Figure 2 may catch
less snow than rain because of the effects of wind. Steps
have been taken, however, to limit this indicator to weather
stations with the most consistent methods and the
highest-quality data. As a result, some parts of the
country have a higher station density than others.
Both figures are limited to the winter season. Figure 1
comes from an analysis of October-to-May snowfall, while
Figure 2 covers November through March. Although these
months account for the vast majority of snowfall in most
locations, this indicator might not represent the entire
snow season in some areas. Most of the data shown for
mountainous regions come from lower elevations (towns in
valleys) because that is where weather stations tend to be
located.
Data Sources
This indicator shows trends based on two sets of weather
records collected and maintained by the National Oceanic and
Atmospheric Administration. Figure 1 was adapted from an
analysis by Kunkel et al. (2009) based on records from
Cooperative Observer Program weather stations. Figure 2 is
an updated version of an analysis by Feng and Hu (2007)
using data from the Global Historical Climatology Network.
Additional information about the Cooperative Observer
Program is available online at:
www.nws.noaa.gov/om/coop. Information about the Global
Historical Climatology Network can be found at:
www.ncdc.noaa.gov/oa/climate/ghcn-daily.
Technical Documentation
Download related technical information PDF |
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 Figure
1. Change in Total Snowfall in the Contiguous 48
States, 1930–2007
This figure shows the average rate of change in total
snowfall from 1930 to 2007 at 419 weather stations in the
contiguous 48 states. Blue circles represent increased
snowfall; red circles represent a decrease.
Data source: Kunkel et al., 20092 |
 Figure
2. Change in Snow-to-Precipitation Ratio in the
Contiguous 48 States, 1949–2016
This figure shows the percentage change in winter
snow-to-precipitation ratio from 1949 to 2016 at 246 weather
stations in the contiguous 48 states. This ratio measures
what percentage of total winter precipitation falls in the
form of snow. A decrease (red circle) indicates that more
precipitation is falling in the form of rain instead of
snow. Solid-color circles represent stations where the trend
was statistically significant.
Data source: NOAA, 20163 |
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EPA Page |
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This is the
EPA page for this topic. To see if the Trump
administration has changed the EPA page, simply click the
link and compare the information with this page. If you
notice changes were made to the EPA page, please post a
comment. Thanks. |
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Additional Climate Change Information |
Climate Change and Carbon Dioxide
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change
and carbon dioxide.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Carbon Dioxide and Climate Change
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of carbon dioxide
and climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
Environmental Group Warns Earth's Health at Risk
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A report by the World Wildlife Fund looked at thousands of animal populations
and found they have dropped significantly in 40 years. |
Sea Levels Rising at Fastest Rate in 3,000 years
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
A group of scientists say sea levels are rising at record rates. Another group
found that January temperatures in the Arctic reached a record high. |
Capturing CO2 Gas Is Not Easy
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Most scientists agree that carbon-dioxide gas is partly to blame for climate
change: rising global temperatures. But capturing the CO2 gas released by power
stations is costly and difficult. |
Growth, Climate Change Threaten African Plants and
Animals
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Researchers believe Africa may lose as much as 30 percent of its animal and
plant species by the end of this century. |
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