Since the World Health Organization has declared the current outbreak of the novel coronavirus (COVID-19) a global pandemic, some have been anticipating that the mitigation could happen in the summer like seasonal influenza, while medical solutions are still in a slow progress. Experimental studies have revealed a few evidences that coronavirus decayed quickly under the exposure of heat and humidity. This study aims to carry out an epidemiological investigation to establish the association between meteorological factors and COVID-19 in high risk areas of the United States (U.S.). We analyzed daily new confirmed cases of COVID-19 and seven meteorological measures in top 50 U.S. counties with the most accumulative confirmed cases from March 22, 2020 to April 22, 2020. Our analyses indicate that each meteorological factor and COVID-19 more likely have a nonlinear association rather than a linear association over the wide ranges of temperature, relative humidity, and precipitation observed. Average temperature, minimum relative humidity, and precipitation were better predictors to address the meteorological impact on COVID-19. By including all the three meteorological factors in the same model with their lagged effects up to 3 days, the overall impact of the average temperature on COVID-19 was found to peak at 68.45 °F and decrease at higher degrees, though the overall relative risk percentage (RR %) reduction did not become significantly negative up to 85 °F. There was a generally downward trend of RR % with the increase of minimum relative humidity; nonetheless, the trend reversed when the minimum relative humidity exceeded 91.42%. The overall RR % of COVID-19 climbed to the highest level of 232.07% (95% confidence interval = 199.77, 267.85) with 1.60 inches of precipitation, and then started to decrease. When precipitation exceeded 1.85 inches, its impact on COVID-19 became significantly negative. Our findings alert people to better have self-protection during the pandemic rather than expecting that the natural environment can curb coronavirus for human beings.

自从世界卫生组织宣布当前的新型冠状病毒 (COVID-19) 爆发为全球大流行以来，一些人一直预计缓解措施可能会像季节性流感一样在夏季发生，而医疗解决方案仍处于缓慢进展中。实验研究揭示了一些证据表明冠状病毒在高温和潮湿的环境下会迅速腐烂。本研究旨在开展流行病学调查，以确定美国 (US) 高风险地区的气象因素与 COVID-19 之间的关联。我们分析了 2020 年 3 月 22 日至 2020 年 4 月 22 日期间美国累计确诊病例最多的前 50 个县的每日新增 COVID-19 确诊病例和七项气象措施。我们的分析表明，在观察到的广泛温度、相对湿度和降水范围内，每个气象因素和 COVID-19 更有可能具有非线性关联，而不是线性关联。平均温度、最低相对湿度和降水是更好地预测气象对 COVID-19 的影响的指标。通过将所有三个气象因素包括在同一模型中并具有长达 3 天的滞后效应，发现平均温度对 COVID-19 的总体影响在 68.45°F 时达到峰值，并在更高的程度上降低，尽管总体相对风险在 85°F 之前，百分比 (RR %) 减少量并未显着为负。随着最小相对湿度的增加，RR %总体呈下降趋势；尽管如此，当最小相对湿度超过91.42%时，趋势逆转。降水量为 1.60 英寸时，COVID-19 的总体 RR % 攀升至最高水平 232.07%（95% 置信区间 = 199.77, 267.85），然后开始下降。当降水量超过 1.85 英寸时，它对 COVID-19 的影响变得非常负面。我们的发现提醒人们在大流行期间更好地进行自我保护，而不是期望自然环境可以遏制人类的冠状病毒。