ChillCast

Know if your fruit trees got enough winter chill. Real weather data, three scientific models, 20 varieties. Free, no ads.

ChillCast tells you whether your fruit trees received enough winter chill to fruit this year.

It pulls real hourly temperatures for your location from Open-Meteo (ERA5 reanalysis) and accumulates chill using the models growers actually use. No guessing, no manual logging.

WHY CHILL HOURS MATTER Deciduous fruit trees 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

• 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. Widely considered the most accurate model for mild climates.

VARIETY MATCHING 20 varieties across apple, peach, cherry, pear, plum, apricot, fig, pomegranate, blueberry, and grape. See at a glance which have met their chill requirement and which are falling short, and by how many hours.

WORKS ANYWHERE Automatic hemisphere detection sets the chill season for you: September to March in the north, March to September in the south. Use your current location or type in coordinates.

FREE

• 45°F Hours accumulation for your location
• Chill requirement matching for 3 varieties
• No ads. No account. No tracking.

CHILLCAST PRO (one-time purchase)

• Unlock all three chill models side by side
• All 20 varieties
• Save and switch between multiple orchards
• Season history chart
• CSV export of daily accumulation
• Notifications when a variety meets its requirement, and a warm-winter alert late in the season when it will not

One purchase. No subscription. Ever.

Weather data by Open-Meteo (ERA5). Chill requirements are representative values from public extension sources and vary by region and rootstock.