Lyman County Climate
Lyman County, South Dakota
NOAA NCEI 1991-2020 Climate NormalsAvg Annual Temp
46.9°F
Annual Precip
20.2"
Annual Snowfall
39.6"
Extreme Heat Days
36
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Growing Season & Gardening
5a
Minimum winter temperature range for plant survival
2,841
Supports most vegetables & fruits
Seasonal Overview
National Comparison
7-Day Outlook
Forecast
Current Conditions
Air Quality
Safety
Weather Alerts
Climate Advisory: Lyman County
Climate Verdict
Lyman County has a cool, averaging 46.9°F annually, semi-arid conditions with only 20.2 inches of annual precipitation, occasional hot days — 36.46666666666667 per year above 90°F, moderate snowfall of 39.6 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.
Seasonal Breakdown
Winters are very cold — January averages 19.6°F. summers are warm — July averages 74.2°F. Residents experience a substantial 55°F difference between winter and summer.
Outdoor & Gardening Guidance
Growing season and gardening data is currently limited for Lyman County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.
Regional Context
Lyman County closely matches the South Dakota statewide average temperature of 45.6°F, it is somewhat drier than average for South Dakota.
Climate Profile
About Lyman County Weather
Warmer and Drier Than the National Average
Lyman County averages 46.9°F annually, placing it well below the national median temperature but higher than many northern peers. The local climate is characterized by low annual precipitation of just 20.2 inches. This creates a semi-arid environment with intense summer exposure.
Outpacing the State in Summer Heat
With an annual average of 46.9°F, Lyman is warmer than the South Dakota state average of 45.6°F. It records a staggering 36 days of extreme heat over 90°F, more than double the count of many eastern counties. Meanwhile, its precipitation levels trail the state average by over two inches.
Central South Dakota's Heat Hub
Lyman County stands out for its high volume of extreme heat days compared to the more moderate eastern counties. Its 39.6 inches of snowfall is significant, even as its total annual precipitation remains a low 20.2 inches. This combination of dry air and heavy winter accumulation creates a rugged climate profile.
Intense Summers and Snowy Winters
July averages reach 74.2°F, fueled by 36 days of extreme heat that push the local climate to its limits. Winter brings a sharp contrast, with a December-to-February average of 21.8°F and nearly 40 inches of snow. These extremes require residents to prepare for both heat waves and heavy drifts.
Managing High Heat and Heavy Snow
Central air conditioning is a necessity in Lyman County to navigate the 36 days of temperatures above 90°F. Reliable winter vehicles are also a must, as the county sees nearly 40 inches of snow and January lows of 19.6°F. Water conservation is often important given the low 20.2-inch annual precipitation total.
Frequently Asked Questions
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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.
Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.