Jack.
I have an Oregon scientific BAA938HG Weather station which "does" measure
outdoor relative humidity.
It has a remote outdoor sensor and I would say that the given accuracy is as
close as I would like it to be considering where its placed. There are so
many considerations to be taken into account on placement of the sensor that
you would need an expert from the met office to come and do a site survey.
Mine cost £89 and I am more than happy with it although the barometric
pressure seems to read about 3 Hpa less than that qouted on the local
forecast but its easy to +3 onto the reading.
Best regards. Len.
"Jack Harrison" wrote in message
...
Oregon makes digital meters giving temperature and humidity but refer the
instruments as being intended to measure indoor humidity.

I am looking for a portable meter that can be used outdoors (with perhaps
a
suitable fan to aspirate). The purpose is to convert the temperature and
humidity into temperature and dewpoint (easily done with tables) and hence
estimate the convective cloud base. In fact, the dewpoint step can be
left
out as temperature against humidity can be used for cloud base direct, but
knowledge of dewpoint is often useful to glider pilots.

I realise that these instruments, while giving a "precision" of 1% /
0.1degree certainly don't offer that level of accuracy. But a calibration
against known readings should enable a reasonable idea of the errors to be
established.

So does anyone have any experience of these cheap and cheerful Oregon
instruments?

Jack