We study the dependence between weekly mortality and temperature through a non-homogeneous Seasonal Hidden Markov Model (SHMM) with trend. The framework jointly models mortality and temperature while allowing for regime switches, explicit seasonality, smooth longterm trends, and time-varying transition probabilities in latent dynamics. We show that the general identifiability and strong consistency results of Touron (2018) apply to our Poissonand Gaussian-emission specifications. We estimate the model on weekly Italian mortality and temperature data using two- and three-state specifications. Empirically, the SHMM improves fit relative to non-switching benchmarks and yields an interpretable state-dependent characterization of the temperature–mortality relationship. We then develop a change-of-measure framework for pricing mortality-linked insurance contracts that incorporates temperature-related mortality risk and latent regime uncertainty.
Kouton, S. D. D., Barigou, K., & Nguyen, T. (2026). Pricing life insurance using bivariate temperature-mortality seasonal hidden Markov models (LIDAM Discussion Paper ISBA 2026/19). https://hdl.handle.net/2078.5/276676