On a 2006 S40 T5, Its normal that when you first start the engine this goes up to 1,400 RPM for less than a minute and then move down by itself to around 800 RPM ?
Its for me a fast starting if the engine its cold and contrary to what I’ve done before with my previous cars, even this did not happen on my previous 2002 S40.
Don’t want the motor been damaged after a few years.
I’ve tried to look over the owner’s manual but couldn’t find any reference, there is only a reference “to not race a cold engine immediately after starting as oil flow may not reach some lubrication points fast enough to prevent engine damage”.
I’ve live on a hot weather area, city altitude it’s around 5,000 ft. (1,500 mts) actually this morning when this happen we were at 75°F (24°C).

I don't think weather has much effect with this because engine gets hot quite rapidly in proportion to ambient air.
From what I've eared it is completely normal. It allows the engine and the turbo to get quickly to temperature thus improving the turbo's life.

Greg

Its just the automatic choke. nothing to worry about.

It is normal to do that, as CJW said nothing to worry about.