Temperature - US Monthly Average

Colors show the average monthly temperature across each of the 344 climate divisions of the contiguous United States. Climate divisions shown in white or very light colors had average temperatures near 50°F. Blue areas on the map were cooler than 50°F; the darker the blue, the cooler the average temperature. Orange to red areas were warmer than 50°F; the darker the shade, the warmer the monthly average temperature.

Temperature readings come from weather stations in the Global Historical Climatology Network. Scientists collect the highest and lowest temperature of the day at each station for the entire month. After they check data quality, they calculate the station’s monthly average and plot it on a gridded map. To fill the grid, a computer program applies a mathematical filter that accounts for the distribution of stations and the terrain. The monthly average temperature for each climate division is the average of all grid point values that fall within it.

Shades of blue show climate divisions that had monthly average temperatures below 50°F. The darker the shade of blue, the lower the average temperature. Climate divisions shown in shades of orange and red had average temperatures above 50°F. The darker the shade of orange or red, the higher the average temperature. White or very light colors show climate divisions where the average temperature was near 50°F.

Tracking average temperature in each of the 344 climate divisions of the contiguous United States gives scientists a way to monitor climate at a regional scale. Energy companies use this information to estimate demand for heating and air conditioning.  Agricultural businesses also use these data to optimize timing of planting, harvesting, and putting livestock to pasture.

Data Snapshots are derivatives of existing data products: to meet the needs of a broad audience, we present the source data in a simplified visual style. This set of snapshots is based on climate division data (nClimDiv) produced by and available from the National Centers for Environmental Information (NCEI) - Weather and Climate. To produce our images, we invoke a set of scripts that access the source data and represent them according to our selected color ramps on our base maps.