The word weather originally had d in place of th. This is visible from the Middle English attestations weder and wedir, as well as from other Germanic languages. For instance, German Wetter can be explained as coming from Proto-Germanic *wedrą. German t usually comes from Proto-Germanic d (that's why English d corresponds to German t in words such as Wort word, reiten ride, Tod death, and Tag day).

So, why did the d in weather change to th?

  • Same as "father" from Middle English fader; "mother" from ME moder; probably "tether" from teder, etc: softening of stop to fricative between vowels, which is very common: see this question on the origin of "mother" and "father", this on d to th sound change; and this.
    – Stuart F
    Commented Apr 24 at 11:52
  • researchgate.net/publication/…
    – TimR
    Commented Apr 24 at 13:01
  • 1
    The opposite change is also attested: /ð/ → /d/ shift in English Confusion seems to have been particularly common in words ending in -der or -ther
    – herisson
    Commented Apr 25 at 22:58

2 Answers 2


The OED says that this was a common sound change first attested in writing around the year 1400 (but doubtless preceding that in speaking) that also occurred in many other similar words of this general form, including also hither and feather, as well as the kinship terms father, mother, brother. All those words in the OED reference a common note in their history of the word father in which these three sentences about the matter can be read:

Spellings with medial th, reflecting the change of postvocalic /d/ to /ð/ before syllabic /r/ or /ər/ (as in mother n.¹, hither adv., weather n.), are securely attested from c1400.

Apparent earlier examples spelt with ð may show transmission errors, either showing a simple error for d (since the letters differ only by a cross-stroke), or reflecting more general confusion of the graphemes ð and d at the point when the former was becoming obsolete.

The English regional (northern) instances with ‑dther may preserve an interim step in the development from /d/ to /ð/, or may reflect a later development arising from association of the form father with words in which th is the reflex of Old English ð; compare similar spellings with ‑dther of e.g. brother n., feather n. Modern regional forms with d either preserve the original consonant or show a subsequent change of /ð/ to /d/ (as e.g. in some northern and north-eastern varieties of Scots).

With respect to interim forms and geographic variance, the written evidence shows that just exactly when and where this happened across Britain varied significantly. Indeed some words which in some writings for a long while enjoyed this same d > th change nonetheless eventually settled on the d version instead of on the th version long used with them. The noun rudder is one of these which commonly enjoyed th for a long while before now being spelt with d.


According to Etymonline the change happened in the late 1400:


Old English weder "air, sky; breeze, storm, tempest," from Proto-Germanic *wedra-

Alteration of -d- to -th- begins late 15c., though such pronunciation may be older (see father (n.)).

The spelling with -th- (15c.) reflects a widespread phonetic shift in Middle English that turned -der to -ther in many words, perhaps reinforced in this case by Old Norse forms; the spelling caught up to pronunciation in 1500s (compare mother (n.), weather (n.), hither, gather).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.