Interval-Censored Survival Analysis of Grapevine Phenology: Thermal Controls on Flowering and Fruit Ripening

Abstract European grapevine (Vitis vinifera L.) is a climate–sensitive perennial whose flowering and ripening govern yield and quality. Phenological records from monitoring programs are typically collected at irregular intervals, so true transition dates are interval-censored, and many site-years are right-censored. We develop a reproducible workflow that treats phenology as a time–to–event outcome: Status & Intensity observations from the USA–NPN are converted to interval bounds, linked to NASA POWER daily weather, and analyzed with parametric accelerated failure time (AFT) models (Weibull and log–logistic). To avoid outcome–dependent bias from aggregating weather up to the event date, antecedent conditions are summarized in fixed pre–season windows and standardized; quality–control filters ensure adequate within–window data coverage. Applied to flowering and ripening of V.~vinifera, the framework yields interpretable time–ratio effects and publication-ready tables and figures. Warmer pre–season conditions are associated with earlier ripening, whereas flowering responses are modest and uncertain in these data; precipitation plays, at most, a secondary role. The approach demonstrates how interval-censored survival models with exogenous weather windows can extract robust climate signals from citizen-science phenology while preserving observation uncertainty, and it generalizes readily to other species and networks.