DOI: 10.3886/e233461
title: Climate.gov Data Snapshots: Temperature - Global Monthly, Difference from Average

description: <b>Q: Where was the monthly temperature warmer or cooler than usual?
</b><b>
 </b><br><b>A: </b>Colors
 show where average monthly temperature was above or below its 1991-2020
 average. Blue areas experienced cooler-than-usual temperatures while 
areas shown in red were warmer than usual. The darker the color, the 
larger the difference from the long-term average temperature.

 
 <br><b>Q: Where do these measurements come from?
</b><b>
 </b><br><b>A: </b>Weather
 stations on every continent record temperatures over land, and ocean 
surface temperatures come from measurements made by ships and buoys. 
NOAA scientists merge the readings from land and ocean into a single 
dataset. To calculate difference-from-average temperatures—also called 
temperature anomalies—scientists calculate the average monthly 
temperature across hundreds of small regions, and then subtract each 
region’s 1991-2020 average for the same month. If the result is a 
positive number, the region was warmer than the long-term average. A 
negative result from the subtraction means the region was cooler than 
usual. To generate the source images, visualizers apply a mathematical 
filter to the results to produce a map that has smooth color transitions
 and no gaps.

 
 <br><b>Q: What do the colors mean?</b><b>
 </b><br><b>A:</b> Shades
 of red show where average monthly temperature was warmer than the 
1991-2020 average for the same month. Shades of blue show where the 
monthly average was cooler than the long-term average. The darker the 
color, the larger the difference from average temperature. White and 
very light areas were close to their long-term average temperature. Gray
 areas near the North and South Poles show where no data are available.

 
 <br><b>Q: Why do these data matter?</b><b>
 </b><br><b>A:</b> Over
 time, these data give us a planet-wide picture of how climate varies 
over months and years and changes over decades. Each month, some areas 
are cooler than the long-term average and some areas are warmer. Though 
we don’t see an increase in temperature at every location every month, 
the long-term trend shows a growing portion of Earth’s surface is warmer
 than it was during the base period.

 
 <br><b>Q: How did you produce these snapshots?</b><b>
 </b><br><b>A:</b> 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. NOAA's Environmental Visualization Laboratory (NNVL) produces the
 source images for the Difference from Average Temperature – Monthly 
maps. To produce our images, we run a set of scripts that access the 
source images, re-project them into desired projections at various 
sizes, and output them with a custom color bar.

 
 
 Additional information
 Source images
 available through NOAA's Environmental Visualization Lab (NNVL) are 
interpolated from data originally provided by the National Center for 
Environmental Information (NCEI) - Weather and Climate. NNVL images are 
based on NOAA Merged Land Ocean Global Surface Temperature Analysis data
 (NOAAGlobalTemp, formerly known as MLOST).

 
 <br><b>References</b>
 
 NCEI Monthly Global Analysis

NOAA View Temperature Anomaly

Merged Land Ocean Global Surface Temperature Analysis

Global Surface Temperature Anomalies

Climate at a Glance - Data Information
 <br>Source: https://www.climate.gov/maps-data/data-snapshots/data-source/temperature-global-monthly-difference-a...<br><br><br>This upload includes two additional files:<br>* Temperature - Global Monthly, Difference from 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-global-monthly-difference-a...)<br>* Cimate_gov_ Data Snapshots.pdf is a screenshot of the data download page for the full-resolution files. <br><br><br>
description: Data is divided in to folders by image resolution -- full size (zip) and large (png). Occasionally there may be one image missing in a particular size but available in another size.<br><br>Data downloaded from climate.gov 6/15/2025-6/18/2025.