Someone sent my daughter a picture of my four-year-old grandson eating lunch with a dozen or so of his fellow pre-schoolers. They’re sitting at a long table, all dressed in the identical white shirts and grey pants or grey jumpers that are the required school uniform.

All but one is also wearing the blue zip up sweater that is optional.

That one is my grandson. The one with roots in the Midwest. The one whose grandmother has not pulled a single piece of wool from the back of her closet in the 13 months that she’s been here.

We check the weather together every day before leaving for school. Rain or rain clouds mean we drive instead of walk. A bright morning sun means I grab a bottle of water to take along. A chill in the air means we go back in and look for the blue sweater. 

Except that last one hardly ever happens. Because every single day feels like t-shirt weather to us. 

I’m beginning to think it’s something that defines us as foreigners. Something akin to the bright white tennis shoes or fanny packs or cameras that can be a dead giveaway at any tourist destination. 

Because the need of a sweater doesn’t seem to be confined to pre-schoolers. Our nanny arrives every morning wearing a jacket. Wool coats and sweaters started showing up on the racks at Liverpool in August. A hand knit wool hat is easier to find in Guadalajara in September than yellow cheese.

The first year we were in Mexico I assumed that the racks of wool meant that a whole lot of people were taking winter vacations to cold weather climates. By now I understand that a lifetime of dramatic changes of seasons has left me immune to the subtle changes that people here notice.

Or, maybe, I’m just so confused about Celsius that I don’t know when to be cold. 

I’m heading to the midwest in a few days to visit family. Leaves will be turning, farmers will be harvesting, football games will be played, and temperatures will be in Fahrenheit.

There’s a good chance I’ll need a sweater.