The virus causing COVID-19 has spread rapidly worldwide and threatens millions of lives. It remains unknown, as of April 2020, whether summer weather will reduce its spread, thereby alleviating strains on hospitals and providing time for vaccine development. Early insights from laboratory studies and research on related viruses predicted that COVID-19 would decline with higher temperatures, humidity, and ultraviolet (UV) light. Using current, fine-scaled weather data and global reports of infections, we develop a model that explains 36% of the variation in maximum COVID-19 growth rates based on weather and demography (17%) and country-specific effects (19%). UV light is most strongly associated with lower COVID-19 growth. Projections suggest that, without intervention, COVID-19 will decrease temporarily during summer, rebound by autumn, and peak next winter. Validation based on data from May and June 2020 confirms the generality of the climate signal detected. However, uncertainty remains high, and the probability of weekly doubling rates remains >20% throughout summer in the absence of social interventions. Consequently, aggressive interventions will likely be needed despite seasonal trends.

引起 COVID-19 的病毒已在全球范围内迅速传播，威胁着数百万人的生命。截至 2020 年 4 月，尚不清楚夏季天气是否会减少其传播，从而减轻医院的压力并为疫苗开发提供时间。实验室研究和相关病毒研究的早期见解预测，COVID-19 会随着温度、湿度和紫外线 (UV) 的升高而下降。利用当前的精细天气数据和全球感染报告，我们开发了一个模型，该模型可以解释基于天气和人口统计 (17%) 以及特定国家影响 (19%) 的 COVID-19 最大增长率的 36% 变化。紫外线与 COVID-19 生长速度降低的关系最为密切。预测表明，如果不进行干预，COVID-19 将在夏季暂时减少，到秋季反弹，并在明年冬季达到峰值。基于 2020 年 5 月和 6 月数据的验证证实了检测到的气候信号的普遍性。然而，不确定性仍然很高，在没有社会干预的情况下，整个夏季每周翻倍率的可能性仍保持在 20% 以上。因此，尽管存在季节性趋势，但仍可能需要采取积极的干预措施。