UHT cream storage - temperature extremes
I couldn't find any recent scientific literature on UHT cream, but I did find a bit on UHT milk.  And at least what's said about milk indicates that it should be fine being stored up to 37C.  This study says that shelf life is shortened above 30C, but that &quot;shortened&quot; still means 4-5 months.  And this one(pdf), from Sudan, found that a &quot;room temperature&quot; of 33C for UHT milk didn't hurt quality at all within 90 days.
However, that's milk.  What do we know about cream?
This old study suggests that UHT Cream has a significantly shorter shelf life than UHT Milk, and that it's a lot more affected by temperature.  In that study, you can see that flavor declines a lot faster at 18C than at 4C, and that separation of the cream happens at 18C in as little as 4 weeks.  While there's no data on storage at 30C, one would expect it to separate even sooner, maybe in as little as a week.  If you can get access to the Journal of Dairy Science, they may have more updated articles on UHT Cream shelf life.