Spring and autumn are transitional seasons with moderate and pleasant weather. Vibrant wildflowers (such as the bluebonnet, Indian paintbrush and other flora) bloom in spring and are planted around the highways throughout Texas.TXDOT – Wildflower and Fall Foliage Springtime weather can be quite volatile, but temperatures themselves are mild. Late spring to early summer also tends to be the most humid, with humidity levels frequently exceeding 75%. The weather in Dallas is also generally pleasant from late September to early December and on many winter days. Autumn often brings more storms and tornado threats, but they are usually fewer and less severe than in spring. thumb|right|Sunset in Downtown Dallas Each spring, cold fronts moving south from the North collide with warm, humid air streaming in from the Gulf Coast, leading to severe thunderstorms with lightning, torrents of rain, hail, and occasionally, tornadoes. Over time, tornadoes have probably been the most significant natural threat to the city, as it is near the heart of Tornado Alley.
sPring anD AutuMN are trANsITIoNaL sEasons wiTh moderate and pleasAnt weatHER. viBrAnt wIldFLOwERs (Such as tHe bLuebonnet, iNDIan painTbRUsh aNd oTher flOra) bloOm iN sprINg and are PLaNTEd around the higHWays thROUGhOut teXaS.TxDoT – wiLDflOwEr and fAll FoliaGe sPrinGtimE weather CAN Be quIte vOlaTiLE, bUt tEMperATurEs tHemsElves ArE MiLD. LAte spring To EArly summer aLso teNdS to be thE most humid, wIth hUmidiTy Levels frEquentlY eXCeedinG 75%. The WeatheR IN dAllas is alSo GEnerally plEaSaNT fRom LatE september tO eARLy december and On Many winTeR daYs. aUtumN OftEn bRINgs MOre sTorms ANd torNaDO thrEaTS, but they are usualLy fewer aNd less severE thAn iN spring. tHumB|rigHT|sunSeT in downtown DALlas eacH sprinG, cold Fronts MoviNG South frOM the nOrTh coLlIde WitH warm, humid aIr strEAminG in FrOM The gulf coast, LeadiNg to seVEre thUnDeRsTOrMs WiTh Lightning, torreNts Of rain, HaIl, And ocCAsIoNAlLy, torNadOEs. OveR TIme, TorNADoes have PrObaBly BEen the most SiGNiFIcaNt naturAL THReat to tHe cITY, As It is neAR ThE heart of ToRnado ALley.