
Certified GKH Gardening Expert
Your temperature highs in summer match those of my area here in the united States. This is a very important factor when choosing when to plant something, but the other question will be... How cold will it get in your area? Likely, if it does not freeze at all in your area, then your best bet will be to plant anytime that it is not above about 30c.
If you do experience colder weather as well, then just make sure to give it at least 2 months to settle in before a frost.
This article will give you more information about these trees:https://www.gardeningknowhow.com/ornamental/trees/elm/camperdown-elm-tree-information.htm