OK, here is how I configured this in Cacti. It's been a while, so I hope I haven't forgotten anything.
First create a host/device for the weather station:
Most important here is the SNMP time-out and max OIDs per request. The defaults did NOT work for me. I had to increase the timeout to 1500 (1.5sec) because the Arduino takes quite a while to reply (roughly one second in my case). It also only supports one OID per request, so enter 1 in that field.
Then you need to configure one data source per value. Here is an example:
Select the host you just created and then enter the OID for that specific value.
Then you need a graph template. You can use an existing one to start with and modify it (or leave as is for the beginning)
I have also created a CDEF entry that divides all received data by 100. That is because I'm sending the temperature values from the weather station in 100th of a degree. So a returned value of 1 means 0.01 degree. That is because SNMP only knows integer numbers.
Here is the CDEF I added:
The CDEF is then applied to every item in the graph template:
Clicking on each of the items will show this screen:
Then it's time to create the actual graph:
Here everything comes together. Select the graph template that you created/want to use, select the host and then the data source.
OK, that's it. You should now get some graphs. Cacti only sends SNMP requests every 5 minutes. So give it some time to collect some data. Graphs will not appear until at least one value has been recorded.
I hope that helps a little. Just ask if you have any questions....
I will post the sketch when I get home. I have no access to that file here at work..