using macbook outside?

Depends on what "outside means".

UV tends to slowly cause damage to a lot of things. I'd avoid intense sunlight. Not to mention that the aluminum could get very hot like a car dashboard.

If it rains it wouldn't be good. If it's windy and dusty - that wouldn't be good. Definitely don't use it on a windy beach or any place there's a lot of sand. You wouldn't want sand to get in the optical drive.

Outdoor cafe - good weather - with an outdoor umbrella or filtered sunlight should be fine. Of course spilling coffee would not be a good thing.

I agree with y pw. It all really depends on where you intend on using it outside. If by "outside", you're talking about a little chair outside a coffee shop, or around the campus of a University (all in good weather), then there is absolutely nothing wrong with that.

Direct sunlight is okay, unless you leave it sitting there for extended periods of time.

If anything, the sole reason you should not have your MacBook outside in bright sunlight is the glossy screen's glare. It is much more difficult to see the screen clearly under those conditions.

Happy to help.

Perhaps then you should mark this question as solved. 😉