What are the 'dog days' of summer?
The 'dog days' are the hottest weeks of summer — the Romans linked them to the dog-star Sirius rising with the sun (roughly July 3 to August 11). Brewer's Dictionary of Phrase and Fable (1898), human-proofread transcription on English Wikisource records: “Days of great heat. The Romans called the six or eight hottest weeks of the summer canicula′rēs diēs. According to their theory, the dog-star or Sirius, rising with the sun, added to its heat, and the dog-days bore the combined heat of the dog-star and the sun. (July 3rd to August 11th.)”
Origin
- Verbatim from Brewer's (1898): Days of great heat. The Romans called the six or eight hottest weeks of the summer canicula′rēs diēs. According to their theory, the dog-star or Sirius, rising with the sun, added to its heat, and the dog-days bore the combined heat of the dog-star and the sun. (July 3rd to August 11th.)
How to use it
- Modern usage: The 'dog days' are the hottest weeks of summer — the Romans linked them to the dog-star Sirius rising with the sun (roughly July 3 to August 11).
- When quoting the origin, cite Brewer's Dictionary of Phrase and Fable (1898) — this is a 19th-century record, not a modern etymology.
Source:
Last verified: 2026-07-18
- Definitions and origins are drawn from public-domain reference works, primarily Brewer's Dictionary of Phrase and Fable (1898), with modern usage notes clearly marked.