To cite package ‘degday’ in publications use:

  Lyons A (2022). _degday: Compute Degree Days_. R package version
  0.4.0.9000, <https://github.com/ucanr-igis/degday>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {degday: Compute Degree Days},
    author = {Andy Lyons},
    year = {2022},
    note = {R package version 0.4.0.9000},
    url = {https://github.com/ucanr-igis/degday},
  }