Background: One important worldwide health concern that has quickly moved to the top of the global health agenda is climate change. It affects a person's physical, psychological, and social well-being. The study aims to assess the maternity nurses' competencies regarding the potential consequences of heat exposure on mothers and newborns in the face of climate change. Design: A descriptive cross-sectional study design was used. Settings: The study was conducted at Shebin El-Kom Teaching Hospital and University Hospital in the Menoufia Governorate, Egypt. Sample: A convenient sample of fifty maternity nurses was recruited. Instruments: Three instruments were used to gather data: a self-administered questionnaire about the personal data of maternity nurses; a self-administered questionnaire about the maternity nurses' knowledge of the potential health effects of heat exposure on expectant mothers and newborns' health in the context of climate change; and a self-administered questionnaire about the maternity nurses' practices regarding the potential health effects of heat exposure on expectant mothers and newborns' health in the context of climate change. Results: the average overall knowledge is 36.40 ± 7.84, resulting in a total percentage score of 54.0%, reflecting a good level of knowledge, while the overall practices of maternity nurses regarding the potential consequences of heat exposure on the health of expectant mothers and newborns in the face of climate change exhibit unsatisfactory practices (92.0%), with an average score of 8.76 ± 2.65. Conclusion: The study findings concluded that maternity nurses had a fair level of knowledge and unsatisfactory practices overall. Consequently, a disparity exists between knowledge and implementation. Recommendations: Organize educational programs and training workshops by maternity health authorities to increase nurses' understanding of the effects of climate change on mothers and newborns in the face of climate change.