In article ,
Jeremy Handscomb writes:
For instance I have decided
to record the minus 3 deg only once (for the 15th) and allow last night's
minimum of minus 0.5 deg to stand as the minimum for the 24-hour period 0800
(16th) - 0800 (17th). I know that this is not accurate to the convention,
but for my own personal records, I feel that I would like to know that the
temperature didn't fall to minus 3 deg two nights in a row (as Keiron
pointed out).

Why not maintain two sets of data so you can record it both ways, and
get the best of both worlds as it were? Or would that be too much work?
--
John Hall "[It was] so steep that at intervals the street broke into steps,
like a person breaking into giggles or hiccups, and then resumed
its sober climb, until it had another fit of steps."
Ursula K Le Guin "The Beginning Place"