A southeasterly airflow over Canterbury on Sunday is expected to bring much colder conditions as sub-polar air moves into the region.

Blue Skies Weather & Climate Services Ltd reported that widespread rain, possibly heavy at times, is likely throughout the day, with snow levels lowering in the afternoon and evening across the Canterbury High Country and Plains.

For farmers, snow is anticipated to lower during the afternoon, with brief heavy falls possible at higher elevations later in the evening. Snowfall could reach as low as 300 meters.

Snow showers are expected to clear early on Monday, followed by several days of frost.

The period from late Saturday through early Monday may pose a hazard to newborn stock due to the combination of rain, snow, very cold temperatures, and strong winds.

Snow may also affect mountain passes later on Sunday, according to Blue Skies Weather & Climate Services Ltd.