Snow Cover

Latest Score:


in 2019

Weight: 8%
score trend is flat over time

Snow cover is projected to decrease in depth, duration, and extent under climate change. Lack of sufficient snow cover can make tree roots vulnerable to freezing damage and cause nutrients to be leached from the soil1,2,3. Also, the melting of snow in late winter can provide a steady supply of water to trees when they are preparing for bud break. Snow cover fluctuations above or below the mean may result in undesirable conditions for native forest species. Here, snow cover is defined as the number of days with snow cover greater than 1” in depth for Vermont. As trees are adapted to the conditions they have experienced, deviations in snow pack from the long-term mean (both above and below) could be problematic to forests. A high score means snow cover is near the long-term mean.

1Decker, K.L.M., Wang, D., Waite, C. and Scherbatskoy, T., 2003. Snow removal and ambient air temperature effects on forest soil temperatures in northern Vermont. Soil Science Society of America Journal, 67(4), pp.1234-1242.
2Groffman, P.M., Driscoll, C.T., Fahey, T.J., Hardy, J.P., Fitzhugh, R.D. and Tierney, G.L., 2001. Colder soils in a warmer world: a snow manipulation study in a northern hardwood forest ecosystem. Biogeochemistry, 56(2), pp.135-150.
3Rustad, L., Campbell, J., Dukes, J.S., Huntington, T., Lambert, K.F., Mohan, J. and Rodenhouse, N., 2012. Changing climate, changing forests: The impacts of climate change on forests of the northeastern United States and eastern Canada.

Snow cover is decreasing, as winter temperatures warm and less precipitation falls as snow, and the snow that does fall is melting during warm-ups and not accumulating. This lower snow cover leads to earlier spring melt and dryer summer soils. This can lead to drought and a longer wildfire season.

Additional Resources

National Climate Assessment 2014

National Climate Assessment 2018

NCEI State Summary for VT

Interpretation provided by:

NOAA, Northeast Regional Climate Center at Cornell University (2020)


The score is calculated using a target value and the historical range of the the entire long-term dataset. The higher the score, the closer this year's value is to the target.

Once the score is computed for each year, the trend in scores over time is calculated. If the trend is significantly positive or negative, the long-term trend is marked as increasing or decreasing respectively.

Component Description
Scored as

Distance away from long-term mean (scaled 1-5)

Target value

Long-term mean

Directionality of scores

No change from the long-term mean is better.

Minimum value used in scoring

Data minimum - 10% of range

Maximum value used in scoring

Data maximum + 10% of range

The total annual number of days with snow cover >1 inch in Vermont were collected from NOAA National Centers for Environmental Information1. We set the target for the dataset as the mean duration of snow cover from 1961-1990 which is used as the baseline normal for climate comparisons by the Intergovernmental Panel on Climate Change (IPCC). The current year is scored for where it falls between the target and the upper scoring bounds (maximum value in the dataset) or the lower scoring bounds (minimum value in the dataset), scaled to be between 1 and 5.

1 NOAA National Centers for Environmental Information. 2019. Available at: