This depends on the rest of the cable route, and the termination detail.  a multi core cable with the 3 or 4 cores side by side may reach 90C with a given current flow, in a given environment - say attached to a wall or in a duct. The hottest part of the cable must be kept below 90C, but that may not mean the  ends are that hot..

It is not going to be the same once the cores have been split out, as generally that is cooler, or need  if part of the cable or cores is clamped to something that is a better heatsink than the rest of it.
And then the box with terminations itself may be in a hotter or colder place. It is not a simple matter to determine.
Mike

BS 7671 states that switchgear, protective devices and accessories shall not be connected to conductors intended to operate at a temperature exceeding 70 degrees unless the equipment manufacturer has confirmed that the equipment is suitable for such conditions. Hence we use the 70 deg CCC values when using XLPE 90 deg cable.

The confusion is that the switchgear for example is tested under BS EN 61439-2 which allows a 70 degree rise on the terminals - BUT - with a maximum ambient temperature of 35 degrees. Therefore the terminals during testing could potentially be at 105 degrees...?

Possibly there's a slight lack of co-ordination between standards - BS 7671 talks about terminals being suitable for conductors that operate at over 70 degrees (i.e. 70 degrees refers to the notional temperature of the conductor, rather than the terminal) while the other standard seems to be talking about temperature of the terminal itself. Each temperature is the result of the balance of the heat generated (by the conductor in the case of the cable, or from fuse or thermal elements of CBs and their associated conductors) verses available heat dissipation. Then there are a few other 'variables' to throw into the mix - typically conductor temperatures are calculated for a set of conductor bunched together (e.g. in a multicore cable or conduit) - whereas a single core on its own going to a MCB terminal is likely to run substantially cooler. But then the conductor will likely act as a heatsink for some of heat created by the protective device - which will in turn help limit the terminal temperature. So comparing a 70-degree cable with a 105 degree (or whatever) terminal is a bit like trying to compare apples with pears - as the temperatures a really just nominal values for different reference conditions.

Generally the 90 degree rating is most useful where installation conditions change along the run of the cable - in many cases where conditions mid-run are less favourable than at the end, you can make use of the 90-degree rating for those parts while still keeping it at a nominal 70 degrees for the terminations.

    - Andy.