Fine　particulate　matter　(PM2.5)　poses　a　risk　to　human　health.　In　January　2017,　the　PM2.5　pollution　in　China　was　severe,　and　the　average　PM2.5　concentration　had　increased　by　14.7%　compared　to　that　in　January　2016.　Meteorological　conditions　greatly　influence　PM2.5　pollution.　The　relationship　between　PM2.5　and　meteorological　factors　was　assessed　using　monitoring　data　and　the　Community　Multiscale　Air　Quality　modeling　system　(CMAQ)　was　used　to　quantitatively　evaluate　the　impacts　of　variations　of　meteorological　conditions　on　PM2.5　pollution.　The　results　indicate　that　variations　of　meteorological　conditions　between　January　2017　and　January　2016　caused　an　increase　of　13.6%　in　the　national　mean　concentration　of　PM2.5.　Unlike　the　Yangtze　River　Delta　(YRD),　where　meteorological　conditions　were　favorable,　unfavorable　meteorological　conditions　(such　as　low　wind　speed,　high　humidity,　low　boundary　layer　height　and　low　rainfall)　contributed　to　PM2.5　concentration　worsening　by　29.7%,　42.6%　and　7.9%　in　the　Beijing-Tianjin-Hebei　(JJJ)　region,　the　Pearl　River　Delta　(PRD)　region　and　the　Chengdu-Chongqing　(CYB)　region,　respectively.　Given　the　significant　influence　of　local　meteorology　on　PM2.5　concentration,　more　emphasis　should　be　placed　on　employing　meteorological　means　to　improve　local　air　quality.