The red-eared slider turtle (Trachemys scripta) exhibits a form of temperature-dependent sex determination (TSD) where exposure to either warm or cool temperatures induce female or male development, respectively. Under constant male producing temperatures, expression of Kdm6b (a histone demethylase) is induced and subsequently initiates testis development by demethylating at the promoter of Dmrt1. Under constant conditions, Kdm6b also displays differential intron retention (IR) where an intron is retained at cool temperatures. Here, we examine Kbm6b expression and IR using ecologically relevant conditions, where embryos are transiently exposed to male and female producing temperatures and show that short exposures to female producing conditions (i.e. heatwaves) eliminates IR in Kdm6b. IR and non-IR Kdm6b transcripts were quantified following exposure to a five-day heatwave at female producing temperatures (29.5 ± 37°C) and compared to embryos incubated under male producing temperatures (25.5 ± 3°C). Exposure to heatwaves resulted in a 10-fold reduction of Kdm6b IR transcripts after only 48 hours of exposure. We then set out to examine whether this effect was driven by thermal cues or underlying hormone signaling. To test this, exogenous estrogens were applied to eggs to induce ovarian differentiation in embryos incubating at male producing temperatures. We are generating expression profiles for Kdm6b in eggs under male, female, and sex-reversed conditions. This study represents the first time that fluctuating temperatures and hormones have been used in concert to characterize the expression of a TSD candidate gene.