Climate.gov Data Snapshots: Temperature - Maximum, 1991-2020 Monthly Average

Principal Investigator(s):  View help for Principal Investigator(s) National Oceanic and Atmospheric Administration

Version:  View help for Version V1

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Climate.gov Data Snapshots: Temperature - Maximum, 1991-2020 Monthly Average 0

Project Citation: 

National Oceanic and Atmospheric Administration. Climate.gov Data Snapshots: Temperature - Maximum, 1991-2020 Monthly Average. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2025-07-03. https://doi.org/10.3886/E235146V1

Project Description

Project Title:  View help for Project Title Climate.gov Data Snapshots: Temperature - Maximum, 1991-2020 Monthly Average
Summary:  View help for Summary Q: How warm do afternoons usually get during this month?
A: Based on daily observations from 1991-2020, colors on the map show the long-term average maximum temperature, sometimes referred to as the daytime or afternoon high, in 5x5 km grid cells for the month displayed. The map reveals the average of daytime high temperatures during the month over the previous three decades.

Q: Where do these measurements come from?
A: Daily temperature readings come from weather stations in the Global Historical Climatology Network (GHCN-D). Volunteer observers and automated instruments collected the highest temperature at each station every day from 1991 to 2020, and sent them to the National Centers for Environmental Information (NCEI). After scientists checked the quality of the data to omit any systematic errors, they calculated each station’s average monthly maximum temperature by taking the sum of all the daily maximum temperatures for a month (for example, all Junes in the 1991-2020 period) and dividing it by the total number of daily measurements (the number of days in the month times 30 years). NCEI scientists then plotted the values on a 5x5 km gridded map. To fill in the grid at locations without stations, a computer program interpolated (or estimated) values, accounting for the distribution of stations and various physical relationships, such as the way temperature changes with elevation. The resulting product is the NOAA Monthly U.S. Climate Gridded Dataset (NClimGrid).

Q: What do the colors mean?
A: The color in each 5x5 km grid cell shows the average of the highest temperature recorded every day of the month for the 30 years from 1991 to 2020. Shades of blue show where the highest daily temperatures measured from 1991 to 2020 averaged below 50°F for the month. The darker the shade of blue, the lower the temperature. Areas shown in shades of orange and red have long-term average maximum temperatures above 50°F. The darker the shade of orange or red, the higher the temperature. White or very light colors show areas where the average maximum temperature is near 50°F.

Q: Why do these data matter?
A: Understanding these values provides insight into the “normal” conditions for a month. This type of information is widely used across an array of planning activities, from designing energy distribution networks, to the timing of crop and plant emergence, to choosing the right place and time for recreational activities.

Q: How did you produce these snapshots?
A: 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 NClimGrid climate data produced by and available from the National Centers for Environmental Information (NCEI). 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.

Additional information
The data used in these snapshots can be downloaded from different places and in different formats. We used this specific data source: NClimGrid Temperature Normals
 
References

Source: https://www.climate.gov/maps-data/data-snapshots/data-source/temperature-maximum-1991-2020-monthly-a...

This upload includes two additional files:
* Temperature - Maximum, 1991-2020 Monthly Average _NOAA Climate.gov.pdf is a screenshot of the main Climate.gov site for these snapshots (https://www.climate.gov/maps-data/data-snapshots/data-source/temperature-maximum-1991-2020-monthly-a...)
* Cimate_gov_ Data Snapshots.pdf is a screenshot of the data download page for the full-resolution files.


Original Distribution URL:  View help for Original Distribution URL https://www.climate.gov/data/Temperature--Monthly--Average-Max-for-1991-2020--CONUS/

Scope of Project

Subject Terms:  View help for Subject Terms climate; temperature
Geographic Coverage:  View help for Geographic Coverage United States
Data Type(s):  View help for Data Type(s) images: photographs, drawings, graphical representations
Collection Notes:  View help for Collection Notes Data is divided in to folders by image resolution -- full size (zip), kml (zip), broadcast (png), small (png), and large (png).

Data downloaded from climate.gov 6/15/2025 - 6/16/2025 (small, large, and full resolution) and 6/21/2025 (broadcast and kml).



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