GOLDEN STATE CLIMATE
California's climate record, what it actually shows, and what can honestly be said about the season and the century ahead.
Two sources, both public, both fetched by scripts in this repository: NOAA's divisional record of California since 1895, and the Climate Prediction Center's index of the tropical Pacific since 1950. Every figure on this site is computed from them when the site is built, and the build refuses to publish if a number in the prose stops matching the number in the data.
One stripe per year
CALIFORNIA MEAN TEMPERATURE, 1895–2025Every year California has been measured, as a single band of colour: blue where the year came in below the twentieth-century average, red where it came in above. There is no axis to read and no line to trace, which is the point — the shape of the century is supposed to be visible before you have decided to look at it.
Four numbers
COMPUTED, NOT QUOTEDEvery figure on this site is computed from the committed data tables when the site is built, and the build fails if a number in the prose stops matching the number in the data. Nothing here is transcribed from a report.
Three questions, three timescales
HOW THE SITE IS ORGANISED"Climate" runs together three questions that have completely different evidence behind them, and conflating them is how a confident sentence ends up resting on nothing. This site keeps them apart, and is honest about which one it can answer well.
The record
131 years of measured temperature and precipitation for California and its seven climate divisions. This is the part the site can answer with real confidence, because it is arithmetic over observations rather than a projection.
Warming Precipitation Drought THE SEASON AHEAD1950–2026Seasonal forecasting
ENSO is the only source of genuine seasonal skill California has, it is far weaker than it is usually made to sound, and it is much stronger in the south than in the north. All three of those are shown here rather than asserted.
ENSO The winter outlook THE CENTURY AHEADMODELLEDProjections
What climate models agree on for California, what they disagree on, and the one result where the disagreement is the finding. Kept clearly separate from the measured record, and never plotted on the same axis as it.
Temperature Precipitation SnowpackThe seven divisions
CALIFORNIA IS NOT ONE CLIMATEA statewide average for California is an average over a rainforest, a desert below sea level and a snowpack at 10,000 feet. It is a real number and it hides almost everything interesting. NOAA cuts the state into seven climate divisions — groups of whole counties, drawn largely on drainage — and every number on this site is computed over one of them.
The ledger, decade by decade
STATEWIDE MEAN TEMPERATUREFourteen decades of the same measurement, each against the twentieth-century average. The 1970s are the last decade in the record to come in below it.
What this site will not do
STATED UP FRONTEvery number is traceable to NOAA/NCEI's published divisional record or to CPC's published ENSO index, and the tools that fetch them are in the repository. There are no hand-entered figures on this site, because the companion site next door found 66 wrong ones the first time it checked hand-entered figures against the real record.
This site has no live observation feed. It cannot tell you what the temperature is, whether it rained yesterday, or how deep the snowpack is this morning — and it will not guess. It also will not attribute a specific event to climate change: that is a formal discipline with its own methods, and running a trend line is not it. Where a claim needs evidence this site does not have, the page says so instead of rounding up.
For current conditions, forecasts and the geography behind them, the companion site is Golden State Weather — same design, same divisions, different question. For official seasonal outlooks, use the Climate Prediction Center.