Chart lesson 1 of 20 · Science
How much has the US warmed since 1895?
A ready-made lesson on one chart of trustworthy public data: read the chart, then discuss the questions. Free, no account needed.
The chart
The interactive chart needs JavaScript. The numbers are on the chart's page.
The contiguous US averaged 54.6°F in 2025. The warmest year since records began in 1895 was 2024, at 55.5°F. Through 2025, the dashed trend line, the straight line that best fits every year, rose about 0.18°F a decade, or 2.3°F since 1895, and warming had sped up to about 0.5°F a decade since 1970. Alaska and Hawaii aren't included.
Source: NOAA National Centers for Environmental Information, Climate at a Glance (Public domain (U.S. government work)) · Data as of Dec 31, 2025
Open the chart and its numbersThe lesson
How to read this chart
Each point is one year's average temperature across the lower 48 states, in degrees Fahrenheit. The axis doesn't start at zero, so a small rise looks steep: read the numbers on the axis, not the height of the line. The dashed line is the trend, the straight line that best fits every year; single years bounce above and below it.
Questions to discuss
- Find the warmest and coolest years on the chart. How many degrees apart are they?
- Why might one year be much cooler than the year before, even while the trend line keeps rising?
- The axis doesn't start at zero here, but bar charts always do. Why is that fair for temperatures but not for bars?
Share it with your class
Post this link in Google Classroom, Canvas or Moodle. Students see the chart, how to read it and the questions; they don't need an account.