The Science of Prediction
Just how good
are woolly worms at predicting weather? Woolly worms have 13 bands, each, potentially, of a different color. These correspond
to the 13 weeks of winter, from December to March.
The darker a band, the colder and snowier the weather. It is as
simple as that!
So here is a complete retrospective on the worms and how they did. Weather figures are those reported at the
mile high U.S. Weather Service Reporting Station on Grandfather Mountain (Banner Elk, NC). Note that the forecasts cover
the season that follows, so that "1978" covers the winter of 1978-79. Accuracy is rated on a scale of 1 to 5, with 1
meaning way off, and 5 close to perfect.
1978 - Brown Sugar
Prediction: Only a very brief description of the prediction survives, simply. "A mild winter."
What happened: The average mean temperature for winter was 33.1 degrees, slightly above normal (which
is 32.4). There was, however, 65.5 inches of snow, 9.3 inches above average.
Accuracy - 3
1979 - Wilson the Woolly Worm
Prediction: Severe cold early in the winter, then a long mild spell in February, followed by a brief
cold snap in March.
What happened: December was above average in temperature, and slightly warmer in January - and February
had colder than normal temperatures! (the mean was 33.9 degrees versus the average of 37.8). March, however, was colder than
Accuracy - 2
Prediction: Bad weather at the start and end of winter with mild conditions in late January and early
What happened: December had fairly mild temperatures, but there was 5.5 inches of snow. March was colder
than normal, with 33.5 inches of snow. The prediction for milder weather in January and February proved true with below normal
Prediction: Early, cold winter with a mild spell in February.
What happened: On target. The snow started in November (with eight inches), then a record 29.5 inches
of snow fell in December. That was about what fell the rest of the winter. February temperatures were 4.4 degrees above normal.
1982 - Name unavailable
Prediction: An extremely cold winter with a Warm spell at the end of February or beginning of March.
What happened: It was cold, but not all that cold - no new low records were set. It was very snowy, however,
with 100 inches of the white stuff falling.
Prediction: Cold and snowy during the first four weeks of winter. Warm conditions in February with more
snow but less severe conditions. The winter will end with a bad snowstorm.
What happened: The first four weeks of winter were not much for snow but cold - and how! Record cold
was reported on Dec. 24 through 26 and 30 and 31, with bitter cold the rest of the end of December. February was above average
in temperature, with almost all the snow (23 inches) of the winter. There were substantial snows in March.
Prediction: Snow at the start of winter, followed by more snow around New Year's Day. Cold and snowy
but not severe weather in January and February. Cold spell in March.
What happened: 34.5 of the winter's 44 inches fell in January and February. There was some snow near
the start, though Christmas was warm. There was a short but incredibly cold period in January as the mercury fell to an all-time
record low of -32 on Jan. 21. February and March were warmer than average.
Prediction: Cold, snowy winter. A mild spell starting in February and continuing to mid-March, followed
by a rough cold snap at the end of the season.
What happened: There was 49.5 inches of snow. February and March were milder, and there was a cold snap
at the end of season: a record of 8 degrees was set on March 22.
Accuracy - 4.5
Prediction: Cold and snowy weather, particularly during the first month and the last three weeks of the
What happened: The snow was there, with 85.5 inches falling. That included a blizzard in the first days
of April. Heavy snow in early January.
1987 - Pretty Cougar
Prediction: Colder than normal temperatures during the first five weeks of winter. A short lull, followed
by two major snow storms.
What happened: January was colder than normal, while February was warmer. There were, several late snowstorms.
Prediction: Colder than normal temperatures during the first five weeks of winter followed by six weeks
of mild weather and two weeks of unusually cold weather.
What happened: Average December temperatures were followed by a warm January, February and March. The
snow came later, starting in February.
Prediction: The first week of winter will be colder than normal, followed by a week of normal conditions.
The next three weeks will be colder, followed by six weeks of normal conditions.
What happened: There was only 33 inches of snow, at least since 1975-76. Temperatures for the season
were at or above normal. Accuracy - 5
1990 - Willie
Prediction: Below average temperatures and snowy conditions for the first four weeks of winter. Normal
winter weather for four weeks, followed by a week of above average temperatures: The final four weeks will be cold and snowy.
What happened: A generally mild winter, with most of the snow coming late.
Accuracy - 3.5
1991 - The Dukester
Prediction: Five weeks of colder than normal weather, followed by five weeks of normal conditions. A
week of mild weather, then two more weeks of cold conditions.
What happened: A relatively mild winter season. The snow came late, and dragged into May.
Accuracy - 3
1992 - Santa's Helper
Prediction: Four weeks of below normal temperatures, followed by three weeks of normal winter weather.
Warmer temperatures in the eighth week of winter then three weeks of average conditions. The last two weeks will have the
worst weather of the winter.
What happened: They call it the Blizzard of '93 - and it happened when the woolly worm predicted. Temperatures
were colder in December than normal, then warmed up in January. February temperatures were just below average.
Accuracy - 5
1993 - Go-Joe
Prediction: Below normal temperatures for the first four weeks, followed by normal temperatures for the
next three weeks. Above normal temperatures in week eight, then back to normal conditions for three weeks. Heavy snow and
cold in the last two weeks of winter.
What happened: The final "heavy" snow did not materialize: only 5.5 inches was reported in March. December,
however, was colder as was January. It did warm up in February.
Accuracy - 3.5
1994 - Robo Worm
Prediction: First four weeks will be cold and snowy, then normal conditions for five weeks. Cold conditions
at the end of winter.
What happened: The winter started a bit late, with slightly above average temperatures in December. The
heavy snow came in February.
Accuracy - 2
Prediction: Below normal cold and snow for the first five weeks. Normal conditions for five weeks, with
three weeks of snow and below normal temperatures to end the season.
What happened: Another woolly winner. The heaviest snow on record was reported, with 116 inches spread
over a whole, long season.
Accuracy - 5
Prediction: The first four weeks of winter will have below normal cold and lots of snow. Normal conditions
for six weeks, followed by two-and-a-half weeks of cold conditions and snow.
What happened: This was essentially the winter that did not happen. Snow was scarce, but some did come
at the end, and winter dragged on long into spring.
Accuracy - 3
1997 - Jake
Prediction: The first four weeks will be cold and snowy, followed by six weeks of normal to mild conditions.
The last three weeks will be wintry.
What happened: The worm was generally right. He was on target in the start of the season, as it was cold
for almost a month, the big blizzard came and then conditions moderated. The stinger at the end, however, only materialized
in part: one week was very cold, the other two seasonal.
Accuracy - 4
1998 - Staley's Comet
Prediction: The first week will be cold and snowy, with below normal temperatures during the second week.
Weeks three and four will be cold and snowy, with normal to above normal temperatures for weeks five to 10. Weeks 11 to 13
to be cold and snowy.
What happened: The worm did a good job of prediction this time. The winter began cold and snowy, followed
by a cold snap in the second week. A warm-up followed, however, contrary to the worm's forecast. Then the critter got back
on track, calling the continued mildness and the fierce return of winter in week 10 of the season. A unique blend of black
and brown stripes at the end was borne out in a series of snow and rainstorms.
Accuracy - 4.5
1999 - Skiddy
Prediction: The first five weeks will be wet and snowy, followed by five weeks of cold but milder weather.
The last three weeks of winter will be snowy, with some cold spells near spring.
What happened: The first two weeks were cold to very cold with some snow, but then things warmed up for
several weeks. The fifth week of winter was cold, but then the milder weather did not appear. The worst of winter was in mid-January,
with very cold temperatures and snow. Week eight was cool, with a little snow. Then temperatures warmed up, and the rest of
winter was mild with rain but only a little snow. Not one of the worm's better years.
Accuracy - 2
2000 - Slick
Prediction: The first week will be cold and snowy, followed by a cold but mild week, then two weeks of
snowy weather. The next seven weeks will be mild, with snow and cold weather to wrap up the last two weeks of winter.
What Happened: The first week was cold with significant snowfall on four days, and the weather stayed
cold throughout mid-January, with two separate snowstorms dumping a total of twelve-and-a-half inches of snow on the region.
February was quite warm with the high reaching 58 and an average temperature for the month of over 48 degrees. There was one
significant snowfall in late February, Slick was a little off in his end-of-winter prediction, as a major snowstorm occurred
in the three days leading up to the next-to-last week. Temperatures were relatively warm, though, so Slick gets points for
coming close on the snow.
Accuracy - 4
Summary - Here are the final results:
Woolly worm predictions were exactly on target eight times out of 23, or 34.8 percent.
Woolly worm predictions were close (4.0-4.9) another five times (21.7 percent).
Woolly worm predictions were right in some areas, wrong in others (3.0-3.9) six times (26.1 percent).
Woolly worm predictions were wrong more than they were right (2.0-2.9) four times (17.4 percent).
Put another way, the woolly worms were close or completely right 57 percent of the time, and more than half
right 82.6 percent of the time.
That is a record of which even professional weather forecasters could be proud!