Chill Hours Calculator — Three Models, From Your Own Temperature Data
Give it an hourly temperature series and a season. You get chill accumulated three ways — the simple 32–45 °F count, Utah chill units, and Dynamic-model chill portions — plotted together, because the three disagree and which one an orchard uses is a decision worth seeing the size of.
Your data
Drop a logger CSV here
HOBOware and Postlad exports are recognised automatically. It is read on this machine — nothing is uploaded.
Synthetic hourly air temperature for one San Joaquin Valley winter, 1 November 2025 to 28 February 2026, written by a logger on a fixed UTC-08:00 with no daylight saving. It contains multi-day tule-fog spells, clear February warm spells above 18 °C — which is where the Utah model starts deducting chill — and a deliberate 62-hour outage in mid-January, so the coverage warning is visible. Generated, not measured.
SVG is vector — scale it to any size in Illustrator, Inkscape or LaTeX without losing quality, and edit the type. Use it unless a journal insists on raster.
Options
Series
Hourly air temperature. Anything finer is averaged to hourly means first.
The three models are defined in °C. A Fahrenheit column is converted, and the figure says so.
Season
A northern season wraps the year end; a southern one does not. Dates are read in the file’s own time offset.
0 is the most recent season the record covers, 1 the one before it.
Models
Both are computed and both are in the totals. This picks which one gets a curve.
Figure
All of that was worked out in this browser tab. Your file was not uploaded, and no request goes out while you work — open the network panel and watch, if you like.