I've not heard there's to be any weather upload with ADSB here in New Zealand.
They have it in the USA on the 978 UAT ADSB system which is only used below 18,000 ft from memory. Basically I think the UAT system is deployed for GA and is only being used to help declutter the 1090 ES ADSB system.
Having the UAT system means running two systems and as far as I know UAT is only being deployed in the USA and perhaps Canada.
I've been told thev1090 system does not have the capability or capacity to upload weather.