The average growing season length has stretched steadily since 1980.
The average growing season length has stretched steadily since 1980.

Farmers who are skeptical of climate change needn’t travel farther than their closest field for evidence of its existence.

Specifically, EPA and NOAA scientists report the average growing season in the contiguous 48 states has increased by 10 days when compared to the long-term average. Much of the increase has happened since 1980.

The average growing season length has grown on both ends, with spring frost arriving later on average, and fall frost also arriving later on average.

The change to growing season length has not been consistent across geographies. The West and parts of the Great Plains saw bigger increases than the Midwest and Southwest, for example. And parts of the Mid-South and Southeast saw neutral or even negative changes to growing season length.

In total, the Western half of the U.S. has seen an average increase of 2.2 days per decade since 1895, while the East saw a 1 day per decade increase over the same time period.

Scientists note that a longer growing season can have both positive and negative implications. On the positive side, it could allow farmers to diversify crops or double-crop over a greater geography. On the other hand, it can increase invasive species, promote weed growth and increase irrigation needs.

Also, there is a positive correlation between rising temperatures and the increase in severe weather events. For example, compare the how the average length of growing season to the number of tornadoes have increased in similar increments.

NOAA has been vocal in its drive toward better “climate preparedness and resilience” under the Obama Administration. To access the agency’s National Climatic Data Center, visit www.ncdc.noaa.gov.