Duluth, MN Climate

Climate Insight: Duluth, MN

The NOAA 1991–2020 climate normals describe Duluth, Minnesota as a location with an annual average temperature of 41°F, ranging from a mean daily high of 50°F to a mean daily low of 31°F. July is typically the warmest month of the year, while January is the coldest. These thirty-year averages, computed from 2 weather stations, smooth out year-to-year variability and give a baseline expectation for typical conditions in any given month.

Beyond temperature, Duluth averages 31.2 inches of precipitation annually, with 90.2 inches typically falling as snow - a real factor for anyone planning to live, garden, or travel here. The frost-free season averages 141 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near May 13 and the first fall freeze near October 1. Turning to energy use, 9,115 heating degree days and 255 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Duluth scores 44/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above turn that into a planning tool: expect the mildest highs and lows in the shoulder seasons, July-driven heat at the peak of summer, and January-driven cold at the depth of winter. Every number here is a thirty-year average, not a forecast, so any given year can and does run warmer, cooler, wetter, or drier than the normal.