Home Depot, Target and Amazon.com all sell thermometers that measure temperatures below zero. All three retailers offer analog and digital options with units in either Fahrenheit or Fahrenheit and Celsius.
Amazon.com offers the greatest range of choices, with hundreds of thermometers and many other forecasting tools, like weather stations, humidity monitors and wind speed calculators. Target and Home Depot have fewer choices, with the first offering 11 thermometers and the second offering 13 thermometers, as of November 2015.
All three retailers offer decorative analog thermometers and thermometers with indoor and outdoor sensor capability where the display is indoors. Target and Amazon.com also provide outdoor digital models with weather-resistant displays.