Squamous cell carcinoma (SCC) is a common skin cancer, often caused by exposure to ultraviolet radiation (UVR). Recent studies have shown that changes in DNA methylation play a crucial role in the development of cancers. However, methylation patterns of SCC are not well characterised. Identifying biomarkers for the risk of developing SCC could be helpful for early detection and diagnosis and can potentially improve treatment and prevention strategies. This study aimed to investigate methylation changes in the epidermis of mice exposed to UVR for 24 weeks. We examined the DNA methylation levels of 260 199 CpGs using the Illumina Infinium Mouse Methylation BeadChip and studied the epidermis of UVR-exposed and unexposed mice every 4 weeks for 24 weeks (n = 39). We identified CpGs with large differences in methylation levels (β-values) between UVR-exposed and unexposed mice. We also observed differences in the epigenetic age of these mice. We identified CpGs in Rev, Ipmk, Rad51b, Fgfr2, Fgfr3 and Ctnnb1 that may serve as potential biomarkers for SCC risk and could be helpful for the early detection and prevention of SCC. Further investigations are necessary to determine the biological functions and clinical significance of these CpGs.