The　sol-air　temperature　is　a　hypothetical　parameter　to　reflect　the　outdoor　multi-field　coupled　thermal　environments　of　air　temperature,　solar　radiation,　and　long-wave　radiation.　The　simplified　model　was　proposed　in　code　for　thermal　design　of　China　which　ignores　the　influence　of　long-wave　radiation　of　sky　and　surrounding　environment.　However,　the　climate　is　characterized　by　strong　radiation,　high　temperature　and　high　humidity　in　tropical　islands,　and　the　underlying　surface　types　are　mostly　sea　surface.　This　may　affect　the　applicability　of　sol-air　temperature　models.　To　explore　the　above　issues,　the　Davis　weather　station　and　Kipp　&　Zonen　solar　radiation　observation　system　were　used　to　gather　the　meteorological　and　radiation　data　around　the　building,　which　is　a　case　study　building　near　the　coastline　in　Sanya.　Also,　the　dynamic　temperature　of　the　external　surface　of　envelope　and　sea　surface　was　captured.　Then,　the　weather　types　were　classified　by　clearness　index,　and　the　influence　of　sky　and　sea　surface　radiation　on　the　sol-air　temperature　calculation　of　each　orientation　in　different　sky　conditions　is　analysed.　The　results　show　that　the　sol-air　temperature　decreased　by　1.07-2.44　°C　on　average　considering　the　long-wave　radiation　of　the　sky　and　sea　surface,　especially　in　clear　sky,　with　an　average　decrease　of　1.49-3.85　°C.　　©　The　Authors,　published　by　EDP　Sciences,　2023.