Excess Urban Heat Mitigation Act of 2023 This bill requires the Department of Housing and Urban Development (HUD) to establish a grant program for state, tribal, territorial, and local governments; metropolitan planning organizations; and certain nonprofits (or consortia of nonprofits) to carry out activities to mitigate or manage heat in urban areas. Eligible activities under the program include the implementation, construction, or maintenance of tree planting, green roofs, shade structures, cooling centers, and community gardens, as well as outreach to the community and education efforts. HUD's Office of Community Planning and Development must coordinate on the program with the Environmental Protection Agency, the National Oceanic and Atmospheric Administration's Climate Program Office, and the Forest Service.