Atmospheric cycles more reliable | Frost the first week of September could be devastating
It’s a commonly held belief in the farming community that there is a greater chance of frost when there is a full moon.
But according to a weather expert, producers should stop looking for lunar guidance.
“The bottom line is there is no statistical significance of a full moon night and a frost or freeze event,” said Drew Lerner, president of World Weather Inc.
“I don’t forecast the weather based on the full moon.”
Lerner’s observation is backed up by a two-page document called Understanding Frost published by Cornell University Co-operative Extension.
“In reviewing weather records of four locations in the (U.S.) northeast for the last 100 years, a full moon did not increase the chance of frost,” said the document.
“It was just as likely to occur when no moon was present as when the moon was full.”
Lerner prefers to rely on what weather patterns are telling him and three separate patterns are “more or less in agreement” that the first week to 10 days of September is the most favoured period for a frost scare in Western Canada.
“It doesn’t mean that there will be a freeze. It doesn’t mean there will be a frost. But it does mean that that’s the next opportunity for a threat of such conditions,” he said.
Lerner is most concerned about an 18 to 19 day weather cycle that brought the last frost scares to the Prairies in July and August. That cycle is scheduled to come back into force around Sept. 3 or 4.
If that weather cycle delivers a killing frost it could be a devastating development for many prairie farmers.
Saskatchewan’s crops were 10 days to two weeks behind normal development as of Aug. 12, according to the provincial crop report.
The normal fall frost date for most of the province is Sept. 9 – 15, according to a 30-year average compiled by Saskatchewan Crop Insurance Corp.
So a killing frost during the first week of September would come a week earlier than normal for a crop that is up to two weeks behind normal. The damage could be extensive if that were to happen.
The last really devastating frost occurred on Aug. 20, 2004. Most of that year’s spring wheat crop fell into the lower three grades, according to the Canadian Wheat Board’s 2004-05 annual report. The production of barley suitable for malt was also significantly reduced.
However, Lerner stressed that forecasting frost is an inexact science.
Another mitigating factor is the streak of hot weather in mid-August that has likely sped up crop development since the last crop report.
“You can certainly see crops really starting to turn quite quickly now, especially once they’re past that filling stage,” said Daphne Cruise, regional crop specialist with Sask-atchewan Agriculture.
Lerner said the second danger zone for prairie crops will be in the last week of September, which would be well past the normal first fall frost date for most regions.
“It would still be significant for the crops that are behind,” he said.
For those who continue to look skyward for guidance, the next full moon is Sept. 19.