ChillCast: Chill Hours Tracker

ChillCast answers one question for your site: did your fruit trees and berries get enough winter chill this year?

Most chill hour guides hand the work back to you. You compare several winters by hand, then hunt for the nearest weather station and hope it is close enough to your block. ChillCast does both parts for you. Give it any location and it pulls hourly temperature estimates for that point from NASA POWER, counts chill with the models growers actually use, and puts ten past winters next to this season.

WHY CHILL HOURS MATTER
Deciduous fruit trees and berries need a minimum amount of winter cold to break dormancy and bloom evenly. Too little chill means delayed, scattered bloom and a poor crop. ChillCast shows where you stand right now.

THREE CHILL MODELS, ALL FREE
- 45°F Hours (Weinberger): counts hours between 0-7.2°C. The traditional standard for cold climates.
- Utah (Richardson): weights temperature bands, and warm spells subtract from your total.
- Dynamic / Chill Portions (Fishman-Erez): handles warm reversals dynamically and is often used in mild-winter regions.

45°F Hours and Utah units are counted Nov 1 to Feb 28 (May 1 to Aug 31 in the southern hemisphere), following UC Davis practice. Dynamic runs Sep 1 to Mar 31 (Mar 1 to Sep 30 in the south).

TYPICAL CHILL FOR YOUR SITE
Ten past seasons for the same point: the average, the coldest and warmest winters, and each season on its own. Outside the counting window ChillCast still answers with those numbers and last winter's result instead of an empty screen.

VARIETY MATCHING
Pick the trees you grow from 124 varieties across apple, peach, nectarine, cherry, pear, plum, apricot, fig, pomegranate, blueberry, grape, persimmon and quince. Every chill requirement carries the published source it came from.

WORKS ANYWHERE
Search by city name, use your current location, or type in coordinates. ChillCast detects the hemisphere and sets the chill season for you.

FREE
- All three chill models for your location
- Typical chill for your site, from ten past seasons
- City name search
- Track up to 3 varieties in My Trees
- Share card image of this season's numbers
- No ads. No account.

CHILLCAST PRO (one-time purchase)
- This season's outlook: the projected season total, and whether each of your trees reaches its requirement
- Variety fit: every included variety rated against your site's typical chill
- Track every included variety in My Trees
- Save and switch between multiple orchards
- This season's accumulation chart and CSV export

One purchase. No subscription. Ever.

Weather data: NASA POWER hourly regional estimates. These are not orchard measurements. Chill requirements are representative values from public extension and nursery sources and vary by region and rootstock. NASA does not endorse ChillCast.