Glossary · Climate

Climate normals

Also called: 1991–2020 normals · 30-year normals · U.S. Climate Normals

Thirty-year averages of temperature, degree-days, precipitation and other weather at a station, used as the typical climate for a place.

What it means

Weather agencies update normals each decade: NOAA's current US set covers 1991–2020. Calculators and audit reports use them for typical heating and cooling degree days, so one unusual year doesn't skew the estimate.

Why it matters in an audit

When a page says a city gets about 4,000 heating degree-days a year, that's a climate normal, so your own year can run colder or warmer.

Typical numbers

Reference values with their sources. Your auditor’s report gives the figure for your own house.

What	Value	Source
US (NOAA)	1991–2020 U.S. Climate Normals: 30-year normals at more than 15,000 stations, over 7,300 of them with temperature normals	ncei.noaa.gov ↗

Sources

Related terms

Heating degree days (HDD) A measure of how cold a place is: each day adds how far its average temperature falls below 65°F. More degree days means more heating.
Cooling degree days (CDD) A measure of how hot a place is: each day adds how far its average temperature rises above 65°F. More degree days means more air conditioning.
Design temperature The cold (or hot) outdoor temperature a heating or cooling system is sized for; colder than most winter days, but not the record low.
Weather normalization Adjusting energy use for how cold or hot a period was, using degree-days, so bills from different years or homes can be compared fairly.
NOAA (National Oceanic and Atmospheric Administration) The US weather and climate agency; its National Centers for Environmental Information publish the climate normals and degree-days used for US cities.

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