Extreme weather events, such as heatwaves, are forecast to increase globally over the coming decades, posing a risk to reproductive health. Our studies show that male reproductive capacity is determined not only by sperm, but also the plasma fraction (seminal plasma, SP) derived primarily from seminal vesicles. In this study, we investigated whether a sub-chronic elevation in ambient temperature can modify seminal vesicle morphology, seminal plasma composition, and/or the subsequent female response to seminal fluid after mating. Adult male Swiss mice were exposed to either control (CT, 21°C) or ‘heatwave’ conditions (HT, 8 hours at 35°C followed by 16 hours at 25°C) for 7 days. Seminal vesicles (SV) were excised for morphological assessment and SV fluid (SVF) was collected, with the major SP signalling factor transforming growth factor beta (TGFB) family measured using Luminex microbead assay. The endometrial response to SP was assessed 8 hours following mating using qPCR. There were no overt changes to seminal vesicle morphology, and heat exposure did not alter the weight of seminal vesicles, or the amount of proteins in SVF. However, heat exposure led to reductions in epithelial cell height (15%, p=0.03) and mucosal folding (23%, p=0.07), and was accompanied by a 1.48-fold increase in TGFB1 (p=0.05) in SVF of HT compared to CT males (n=6-8/group). Additionally, increased expression of the seminal fluid induced cytokines Csf1 (4-fold, p=0.01), Csf2 (22-fold, p=0.02) was observed in the endometrium of female Swiss mice following mating with HT compared to CT males (n=6-8/group). These data indicate that seminal plasma composition is responsive to ambient temperature, and that altered composition of SP in response to a sub-chronic temperature elevation can alter the nature of the female reproductive tract immune response after mating, which in turn has potential to impact fetal development and neonatal outcomes.