14 Nebraskaland • March 2021
IN THE FIELD
By Martha D. Shulski
THE LAST FREEZE
Averages of weather conditions sometimes don't
mean a whole lot in Nebraska. While that is odd
for a climatologist to write, it certainly seems true
in practicality. Any way you examine our weather,
variability reigns. A great illustration is with one
characterization of spring — timing of last freeze.
Spring is considered a shoulder season as we make the
transition from winter to summer. Weather patterns are
active: Winds bring warm southerly air rather than cold
Arctic air, humidity is noticeable, soils thaw and biomes
are brought back to life.
Plant growth begins in earnest after winter's last
chill. The average date of last freeze (32°F) ranges from
mid- to late April in southeastern Nebraska to early June
in the northern Panhandle. High elevation in the west
keeps the probability of freezing temperatures lasting
longer into the season than in the east. The variability
is obvious when we look at the earliest and latest dates
of the last freeze. Going back only four decades, there is
a two-month spread in these dates of occurrence. The
last date for a frosty ground can be as early as the vernal
equinox, March 21 in the east and May 1 in the high
elevation west. It can also occur as late as May 21 in the
east or even summer solstice, June 21, in the west.
Furthermore, even an exceptionally warm spring does
not necessarily translate into a significantly early last
freeze. Take Nebraska's hottest and driest year on record
— 2012. Our spring started out exceptionally warm with
a statewide March temperature that was a whopping 15
degrees above average and new monthly record. When
did we have our last freeze that year? About when we
normally do, April or May depending on your location.
Taking note of the average last freeze date for your area
is appropriate, but the range is probably more so since
variability is the rule in Nebraska, not the exception.
Martha D. Shulski, at the University of Nebraska-Lincoln,
is the director of the Nebraska State Climate office.
PHOTO
BY
JUSTIN
HAAG
