Long-term typology of Almaty thermal regime (1931–2025) based on multidimensional statistical analysis

The aim of the work is to identify statistically justified types of calendar years according to the thermal regime for Almaty city and analyze their temporal dynamics given the modern climate change. A set of multidimensional statistical methods has been applied based on the series of average monthly air temperatures over 95 years: factor analysis (PCA) to reduce dimensionality, cluster analysis (k-means) to classify the years, and discriminant analysis (LDA) to validate the results. The data reliability is confirmed with the high value of the KMO criterion (0.764). As a result, we have identified 5 statistically stable classes of calendar years based on four main components that explain 61.6% of the data variance. The discriminant analysis has confirmed that the classification is 95.8% accurate. The warmest class (with an average annual temperature of 11.3 °C) mainly consists of the calendar years since 1990, which indicates a change in the prevailing climate regime in the late XX - early XXI century, according to the research. The resulting typology reflects a qualitative shift in the thermal regime of Almaty associated with global warming. The selected classes are a practical tool to assess climate risks and develop adaptation strategies for urban management.