Contra Calor

Vineyard GDD & Winkler Tracker

Free · In‑App Purchases · Designed for iPad. Not verified for macOS.

Track Growing Degree Days for any vineyard, anywhere. Station-accurate GDD and Winkler classification for viticulture professionals. Contra Calor is the viticulture Growing Degree Day tracker built for wine professionals. Pin your vineyard, pick your vintage, and get station-accurate heat accumulation data in seconds. WHAT IS GDD? Growing Degree Days (GDD) measure the heat accumulation a vineyard experiences during the growing season. GDD is a primary metric viticulture professionals use to predict grape maturity, plan harvest timing, and benchmark vintages year over year. HOW IT WORKS Drop a pin on your vineyard — anywhere in the world. Contra Calor pulls station-priority weather data from a global network of NOAA, ASOS, and personal weather stations, calculates your GDD accumulation from April 1 through October 31 (or set your own custom date range), and classifies your site on the Winkler scale. VALIDATED ACCURACY Independently validated against CIMIS (California Irrigation Management Information System) stations and Weather Underground personal weather stations across Napa Valley, Sonoma, and the Sierra Foothills. Average variance: 1.5–3.8% against ground truth data. FEATURES - GDD calculation for any vineyard location worldwide - Winkler region classification (Regions I–V) - Save vineyard profiles with nested vintage history - Compare up to 3 vintages side by side - Accumulation curve chart for each vintage - Northern and Southern Hemisphere support - °F and °C toggle - Works offline after initial calculation CONTRA CALOR PRO Upgrade to Pro for unlimited vineyard profiles, full vintage history, 3-vintage comparison, and Southern Hemisphere support. ABOUT THE NAME Contra Calor — Spanish and Latin for both "Against the Heat" and "Counting Heat." Terms of Use: https://contracalor.com/terms.html Privacy Policy: https://contracalor.com/privacy.html

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Bug fixes and improvements: - Fixed an issue where Pro subscription status was not always recognised immediately after purchase - Improved Restore Purchases reliability - Added "Request Pro Access" button for users seeking complimentary access

Version 1.1

The developer, SYBRAND ALBERTUS,STRAUSS VANZYL, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

    Privacy practices may vary, for example, based on the features you use or your age. Learn More

    Accessibility

    The developer has not yet indicated which accessibility features this app supports. Learn More

    Information

    Seller
    SYBRAND ALBERTUS,STRAUSS VANZYL
    Size
    13.2 MB
    Category
    Weather
    Compatibility
    Requires iOS 15.0 or later.
    • iPhone
      Requires iOS 15.0 or later.
    • iPad
      Requires iPadOS 15.0 or later.
    • iPod touch
      Requires iOS 15.0 or later.
    • Mac
      Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    English
    Age Rating
    4+
    In-App Purchases
    Yes
    • Contra Calor Pro $39.99
    • Contra Calor Pro $4.99
    • Learn More
    Copyright
    © 2026 Sybrand van Zyl
  • Developer Website
  • Privacy Policy