Urban　expansion　results　in　landscape　pattern　changes　and　associated　changes　in　land　surface　temperature　(LST)　intensity.　Spatial　patterns　of　urban　LST　are　affected　by　urban　landscape　pattern　changes　and　seasonal　variations.　Instead　of　using　LST　change　data,　this　study　analysed　the　variation　of　LST　aggregation　which　was　evaluated　by　hotspot　analysis　to　measure　the　spatial　dependence　for　each　LST　pixel,　indicating　the　relative　magnitudes　of　the　LST　values　in　the　neighbourhood　of　the　LST　pixel　and　the　area　proportion　of　the　hotspot　area　to　gain　new　insights　into　the　thermal　effects　of　increasing　impervious　surface　area　(ISA)　caused　by　urbanization　in　Fuzhou,　China.　The　spatio-temporal　relationship　between　urban　landscape　patterns,　hotspot　locations　reflecting　urban　land　cover　change　in　space　and　the　thermal　environment　were　analysed　in　different　sectors.　The　linear　spectral　unmixing　method　of　fully　constrained　least　squares　(FCLS)　was　used　to　unmix　the　bi-temporal　Landsat　TM/OLI　imagery　to　derive　subpixel　ISA　and　the　accuracy　of　the　percent　ISA　was　assessed.　Then,　a　minimum　change　threshold　was　chosen　to　remove　random　noise,　and　the　change　of　ISA　between　2000　and　2016　was　analysed.　The　urban　area　was　divided　into　three　circular　consecutive　urban　zones　in　the　cardinal　directions　from　the　city　centre　and　each　circular　zone　was　further　divided　into　eight　segments;　thus,　a　total　of　24　spatial　sectors　were　derived.　The　LST　aggregation　was　analysed　in　different　directions　and　urban　segments　and　hotspot　density　was　further　calculated　based　on　area　proportion　of　hotspot　areas　in　each　sector.　Finally,　variations　of　mean　normalized　LST　(NLST),　area　proportion　of　ISA,　area　proportion　of　ISA　with　high　LST,　and　area　proportion　of　hotspot　area　were　quantified　for　all　sectors　for　2000　and　2016.　The　four　levels　of　hotspot　density　were　classified　for　all　urban　sectors　by　proportional　ranges　of　0%-25%,　25%-50%,　50%-75%　and　75%-100%　for　low-,　medium-,　sub-high,　and　high　density,　and　the　spatial　dynamics　of　hotspot　density　between　the　two　dates　showed　that　urbanization　mainly　dominated　in　sectors　south-southeast　2　(SSE2),　south-southwest　2　(SSW2),　west-southwest　2　(WSW2),　west-northwest　2　(WNW2),　north-southwest　2　(NSW2),　south-southeast　3　(SSE3)　and　south-southwest　3　(SSW3).　This　paper　suggests　a　methodology　for　characterizing　the　urban　thermal　environment　and　a　scientific　basis　for　sustainable　urban　development.