Minnesota and North Dakota Frost Season Lingers Through May 28 While Great Lakes Communities See Final Frost Risks Wrap Up by May 21
MINNEAPOLIS, MN — Frost season is retreating northward but it is not finished yet. Current temperature anomaly data valid for May 16 through May 21, 2026 shows the final frost risks for most of the Great Lakes region wrapping up around May 21, while North Dakota, Montana, and parts of Minnesota face frost risks continuing through at least May 28 and potentially beyond.
Great Lakes Frost Season Closes Out Around May 21
For most residents across Wisconsin, Michigan, Minnesota, and the broader Great Lakes corridor, the window for damaging frost is closing. Temperature anomalies running 2 to 4 degrees below normal across Duluth, International Falls, Bemidji, and Grand Forks during the May 16 to 21 period represent the tail end of frost season for these communities.
Milwaukee, Chicago, Cedar Rapids, and Des Moines are already running near or slightly above normal, indicating frost season has effectively ended for the southern Great Lakes and upper Midwest.
North Dakota and Northern Plains Still at Risk Through May 28
The more persistent cold pool is locked over the Northern Plains, centered across North Dakota, northeastern Montana, and adjacent border areas. Temperature anomalies of 2 to 4 degrees below normal across Bismarck, Fargo, and Brandon keep overnight lows cold enough for frost well into late May.
Current analysis indicates frost risks for this zone continue through at least May 28, with some locations potentially seeing threats extend into early June depending on how quickly the pattern warms.
Frost Risk Timeline by Region
| Region | Frost Risk End Date | Temperature Anomaly |
|---|---|---|
| Chicago, Milwaukee, Des Moines | Already ending | Near to slightly above normal |
| Duluth, Bemidji, Grand Forks MN | Through May 21 | 2 to 4°F below normal |
| Bismarck, Fargo, North Dakota | Through at least May 28 | 2 to 4°F below normal |
| Northern Montana border areas | Potentially beyond May 28 | 4°F+ below normal |
Planting Guidance for Late May
Anyone in North Dakota or northern Minnesota planning to set out tender plants or crops should wait until after May 28 at the earliest. The Great Lakes corridor from Green Bay to Detroit can cautiously begin planting after May 21 but should monitor overnight low forecasts closely through the final week of May.
More weather coverage is always on the horizon. Stay informed at ChicagoMusicGuide.com — your source for frost tracking, seasonal temperature outlooks, and breaking weather coverage across the Northern Plains, Great Lakes, and the entire United States.
