High temperatures correlate with slower Covid-19 infection growth rates

Abstract

This study investigates the relationship between ambient temperature and the rate of growth of Covid-19 infections across countries and U.S. states. Using publicly available epidemiological data from the early months of the pandemic, we perform a cross-sectional analysis showing that higher temperatures are associated with statistically significantly slower infection growth rates. The findings suggest that environmental temperature may be a meaningful factor in the transmission dynamics of SARS-CoV-2, consistent with the known thermolability of coronaviruses and the role of solar UV radiation in inactivating viral particles.

Introduction

As Covid-19 spread globally in early 2020, scientists and policymakers speculated whether the pandemic would exhibit seasonality similar to influenza. Respiratory viruses are known to spread more readily in cold, dry conditions, but whether SARS-CoV-2 would follow this pattern was unknown.

We assembled country-level and U.S. state-level data on Covid-19 growth rates and matched them with average temperature data from the relevant period. We then applied statistical regression methods to assess whether temperature was a significant predictor of infection growth rates, controlling for potential confounders.

Key Findings

• Higher average temperatures were significantly associated with lower Covid-19 infection growth rates.
• The correlation was robust across both cross-country and within-U.S.-state analyses.
• Results are consistent with temperature-mediated effects on viral stability and transmission.
• Findings were published early in the pandemic, providing timely evidence relevant to public health policy.

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