Jimny auto box

Over these last few days with the cold mornings when I've taken my Jimny out first thing the auto box seems to stay in 3rd gear for about half a mile and will then drop into 4th. The speed limit on the road I'm travelling on is 40 mph it's straight and level so I would expect the box to drop straight into 4th. I don't accelerate hard so I don't think it's just staying in 3rd just for acceleration. It's almost as if it has to get warm before behaving normally, for the rest of the day with normal stops there is no repeat of this problem.

I'm not sure if I have a problem or not any suggestions would be welcome

Likely this is supposed to happen to warm the catalyst up.
The Rav-4 won't go into 4th until the temp gauge reads 1/2 way.
The vectra we used to have hung onto all the low gears until it was warm.

It will not go into 4th until the automatic oil have reached a certain temperature. It`s supposed to do so..

Mine did that and I had 25 k on the clock with full sevice history...
I think it is to do with the viscosity of the oil.. An auto clutch is a wet clutch I.E. torque converter which will need warming up to work properly in these cold conditions.
I bet it was fine last summer am I right... There are mini clutch plates that will hold it in the lower gears until enough force exceeds them but with colder conditions the oil in thicker and will hold it in gear for longer untill warmed to the right temperature. Hope this helps. your gaer box oil should be a red colour if its brown. get it replaced. this can be done fully at suzuki or partly at home as you will need special tools to do a proper job of it. Plus it can get abit involved.

Thanks for your replies, they were spot on.

I had to take the Jimny to my local dealer to get the oil checked as I have no where to work.
They said exactly what you said about the oil having to warm up, the oil was ok and the auto box was working within spec.