"Today is the coldest!"
Translation:Heddiw yw'r oeraf!
I typed Heddiw ydy'r oera! and was corrected to Heddiw ydy'r oeraf!
Can the -f of the superlative generally be left off (as I did here), or only in some cases?
Which spelling is better to use in writing -- with -f or without, or doesn't it matter?
Both -a, -af are acceptable. The -a ending is now in the answers.
Either can be used in writing, depending on personal style. -af would be used in anything formal.