What a 30-Year Climate Normal Actually Is

A 30-year average, recalculated once a decade

NOAA's climate normals are the average of a rolling 30-year record, currently 1991-2020, recalculated roughly once every ten years as the window shifts forward. They describe a station's typical climate over three decades, not what happened last year and not a projection of what will happen next year.

Why relocation decisions want a normal, not a forecast

A 10-day forecast answers "should I bring a coat this week." Someone deciding whether to move somewhere, take a job, or sign a year-long lease is really asking a different question: what does a typical year here feel like, month by month, across summers and winters generally, not this specific one. That is exactly what a 30-year normal is built to answer and a forecast is not.

What it deliberately leaves out

A 30-year average smooths over year-to-year swings on purpose, a genuinely unusual summer or a record winter in any single year won't show up here, because the whole point is the typical pattern underneath that noise. Someone who wants to know how last winter actually went, or what this coming week looks like, needs a different source than this site.

Where these numbers come from

Every city page on RealWeatherCheck traces its figures to NOAA's own published normals for its nearest weather station, accessed through NOAA's public BigQuery dataset, not a third-party summary or a scraped average.

Where to go next

See the range this plays out across: Morro Bay, CA, Delavan, WI, Silverthorne, CO.

Why This Uses the Nearest NOAA Station, Not Your Address · How the RealWeatherCheck Comfort Score Is Calculated