I record meteorological data using a 0900-0900 day. If you record a
minimum temperature of, say, 3.5C at 03:30 on 15 January, to which
date is that temperature attributed? Is it the 14th (the date on
which the recording period started) or the 15th (the date on which
the temperature was actually recorded)?

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx*for hourly reports*

Freddie wrote:

I record meteorological data using a 0900-0900 day. If you record a minimum
temperature of, say, 3.5C at 03:30 on 15 January, to which date is that
temperature attributed? Is it the 14th (the date on which the recording
period started) or the 15th (the date on which the temperature was actually
recorded)?

No matter what time the min actually occurs it is attributed to the day on
which the 24-hour recording period ends. In the example you give, it would be
attributed to the 15th.

In Tideswell the min in the 24-hour period ending at 0900z today actually
occurred at 0900z yesterday. Nevertheless, it is attributed to today.

With max temperatures it's different. The maximum during the 0900-0900 period
is attributed to the day on which the recording period starts. In Tideswell the
max in the 24-hour period ending 0900z today occurred at 0325z this morning.
That goes down as the max for yesterday.

These conventions stem from the age before electronic recording instruments.
Max/min temperatures were all manual readings and, at least in the UK, 0900z
became the start/end of the meteorological day.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.

"Freddie" wrote in message
.net...
I record meteorological data using a 0900-0900 day. If you record a minimum
temperature of, say, 3.5C at 03:30 on 15 January, to which date is that
temperature attributed? Is it the 14th (the date on which the recording
period started) or the 15th (the date on which the temperature was actually
recorded)?

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx for hourly reports

For stations recording data for climatological purposes, readings are made
at 0900z daily.
Minimum temperatures and grass min read at 09z are attributed to the day
that they are read. Maximum temps and rainfall (amount and duration) are
attributed to the previous day (thrown back). Days of thunder, snow or hail
are attributed to the day on which they occur, period 00-24. Days with fog,
snow lying, for climatological stations, are recorded if the conditions are
met at 0900 z. Earth temperatures are read at 0900z.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html

On 3 Jan 2013 15:22:20 GMT, "Norman" wrote:
No matter what time the min actually occurs it is attributed to the
day on
which the 24-hour recording period ends. In the example you give,
it would be
attributed to the 15th.

With max temperatures it's different. The maximum during the
0900-0900 period
is attributed to the day on which the recording period starts.

Thanks Norman and Bernard. I thought this was the case.

--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx*for hourly reports*