Evaluating Fall Frost Risk to Your Crops

By Tyce Masich, AAg, Crops Extension Specialist, Moose Jaw

September 2025

Harvest is in full swing across Saskatchewan and cool fall temperatures are beginning to set in. Producers need to assess the risk of fall frost in their crops so potential action can be taken to limit its damaging effects.

For much of the province, summer temperatures were cooler than previous years which slowed crop development and pushed back harvest. According to the Crop Report, harvest is behind five- and 10-year averages in 2025 and only 41 per cent of crops were harvested when the first frosts hit the province in early September. This means many acres of pulse, cereal and canola crops were in the field and could have experienced damage when temperatures dipped below zero. Many parts of the province have already had nights with sub-zero temperatures, with areas in northern and eastern regions reporting the most frost damage in crops. Producers are encouraged to scout crops for damage and monitor the forecast during harvest.

Preventative measures that can be taken to mitigate the risk of frost damage depend on the crop. Canola is prone to frost damage when the moisture content is above 20 per cent and early swathing may protect yield if crops are swathed at least 72 hours before freezing. However, early swathing can hurt yield, so this should only be considered if a major freezing event is in the forecast.

There isn’t much that can be done to mitigate the risk of fall frost damage in cereal crops. As the crop matures into the hard dough stage, it becomes more tolerant to freezing temperatures. Freezing in earlier dough stages may cause kernels to shrivel which hurts the quality and yield of the crop. Additionally, freezing temperatures can lower the viability of seeds being replanted. Producers should test their seed for germination and vigor if they are considering planting frost-damaged kernels in the future.

Frost can cause lentil and pea seeds to become water soaked. Damage occurs in these crops when temperatures reach -2°C during flowering and -3°C to -4°C during podding. Soybeans are prone to yield loss when temperatures dip below -1°C for an extended period.

Monitoring the weather forecast and scouting fields after frost is essential for producers to determine how freezing temperatures may affect their crops. To learn more about fall frost, please contact your local crops extension specialist at your local regional office.