Cumulus temperature reading variations.

[Touchtone]

I am using a Davis VP2 Plus & Cumulus with 15 minute archive & also checking with readings in Weatherlink also on 15 minute archive & they don't show the same Maximum temperature.

The readings are as follows:
Cumulus. Max temp for 18 April 29.9 c at 1:56 pm. Weatherlink. Max temp 18 April 30.1 c at 2:30 pm.
Cumulus. Max temp for 19 April 29.8 c at 2:00 pm. Weatherlink. Max temp 19 April 30.2 c at 2:00 pm.

The Davis console agrees with the Weatherlink result, so I am wondering why Cumulus doesn't report the same information.

I don't have my computer on all day & I start Cumulus in the morning first & peruse through the information & then close it & switch over to Weatherlink & do the same there. So Cumulus downloads the data first & Weatherlink also downloads later when I start it. I am certainly not trying to run them both at once as that can't be done.

Perhaps someone can help here as I feel the readings should be identical.

[steve]

Cumulus and Weatherlink work in completely different ways, so the timestamps and readings will sometimes be slightly different, particularly if you're not running them at the same time (which can be done using Virtual VP, although there are issues with doing that), and when logger data is involved. Weatherlink only works with Davis stations and uses all of the data that the console makes available - the highs and lows etc. Cumulus works with several different types of weather station, so there has to be a compromise. It accumulates its own highs and lows. If you run Cumulus 24/7 it will get all of the highs and lows correct.