I live in Lake Havasu City. I have 3 Eucalyptus trees that I want to top about 5 feet off this week. My tree service says I should be ok, but I was reading that it is best in summer. The reason I want to do it now is we need the shade in summer and give them a chance to fill out. Our highs this week in the 70's and lows in the 50's. Maybe late next month we could see some lows of in the 30's but highs 60's. I would really appreciate your advice.
Eucalyptus are best pruned in the summer. This is different from most other trees, that do best when pruned very early in the spring. If you prune at the recommended time, the trees will probably put out new growth very quickly, and there will be less chance of disease. If the shade is a little too small that first year, you can probably find a simple awning that will temporarily help you out. This article has more information on eucalyptus pruning: https://www.gardeningknowhow.com/ornamental/trees/eucalyptus/eucalyptus-pruning.htm