Surprise Late-May Frost Sweeps Minnesota — What It Means for Your Garden, Crops & Morning Commute

A late-season chill is poised to sweep across Minnesota this week, and the National Weather Service (NWS) has issued multiple Frost Advisories that could spell trouble for gardeners and farmers who already put tender plants in the ground. Overnight lows are forecast to dip into the mid-30s across northern and central counties, with sheltered lowlands flirting with the freezing mark—cold enough to damage emerging corn, soybeans, flowers, and fruit blossoms. Key details of the advisory • Timing: 10 p.m. to 9 a.m. through at least Thursday, with updates expected daily. • Affected areas: Duluth, Brainerd, Bemidji, Grand Rapids, and portions of the Iron Range; patchy frost is also possible as far south as St. Cloud and the northern suburbs of the Twin Cities. • Temperatures: 32°–36°F in most locations, but pockets in the Arrowhead region could briefly reach 30°F. Why this frost is unusual Minnesota typically sees its final spring frost in early to mid-May. By late May, most gardeners breathe a sigh of relief, so a fresh round of advisories just days before Memorial Day is a statistical outlier. Historical climate data from the Minnesota DNR show only a 10-to-20 percent chance of frost after May 20 in much of the state, underscoring how rare this event is. Impacts on agriculture Agronomists warn that newly emerged corn and soybeans are vulnerable once temperatures fall below 28°F for more than a couple of hours. While this week’s chill is expected to hover a few degrees above that threshold, low-lying fields could still experience localized freeze pockets. Fruit growers face a similar threat: apple, cherry, and plum blossoms can suffer significant yield loss if exposed to temps below 34°F for an extended period. University of Minnesota Extension recommends using wind machines, row covers, or even overhead irrigation to protect high-value crops. Home gardening tips 1. Cover tender plants: Use lightweight fabric, old bedsheets, or frost cloth. Avoid plastic touching foliage—it can transmit cold directly. 2. Water before sunset: Moist soil retains daytime warmth and radiates it upward overnight, moderating exposure. 3. Move containers indoors: Potted tomatoes, peppers, and herbs can be shifted into a garage or porch until the advisory expires. 4. Delay warm-season planting: If you haven’t transplanted eggplants, cucumbers, or annual flowers yet, consider holding off until the weekend when overnight lows rebound into the mid-40s. Travel and outdoor recreation Frosty mornings can produce slick spots on rural bridges and elevated roads, especially in northern Minnesota. Campers heading to the Boundary Waters should pack cold-weather gear; temperatures near Ely could settle near the freezing point at sunrise. Outlook for the rest of the week A strengthening Canadian high-pressure system is driving the cold air south. Meteorologists expect gradual moderation beginning Friday, with daytime highs climbing back into the upper 60s and overnight lows staying safely above 40°F statewide by Sunday. However, another weak front early next week could reintroduce scattered frost north of Highway 2, so gardeners should monitor updates. Climate context Late-May frost events are becoming less frequent overall, but when they do occur they can be especially disruptive because planting calendars have shifted earlier in response to warmer average springs. “Producers are taking advantage of those warmer trends, so any cold snap that sneaks in after mid-May now has higher stakes,” said Pete Boulay, state climatologist for the Minnesota DNR. What to watch next • Updated advisories: The NWS offices in Duluth and the Twin Cities will refine timing and coverage as new model data arrive. • Crop insurance claims: If sub-freezing pockets develop, early reports of frost-nipped corn and soybeans could surface late this week. • Memorial Day weekend: A milder pattern should return just in time for holiday travel and gardening catch-up, but another temperature dip cannot be ruled out. Bottom line Minnesotans shouldn’t panic, but they should act quickly. A simple bedsheet tossed over tomatoes tonight could be the difference between a thriving garden and a replanting headache. Keep one eye on the thermometer and the other on weather alerts—spring may be nearing its unofficial finish line, but Mother Nature isn’t done with her plot twists just yet.