It was 24C (75F) in New York last weekend, triggering a very particular New York response. As families flooded Central Park for what felt like the first nice day of spring, the compulsion to enjoy the weather was followed by an equally strong compulsion to speculate that tomorrow, in all likelihood, it would rain. This is the great qualifier to American optimism – neurosis – and it shares a reflex with British defeatism. The difference between the two is in what happens next.

When I first moved here, I remember thinking the tendency of New Yorkers to fixate on “solutions” was a noble but misguided impulse. Like British people, New Yorkers can look at a scene and immediately identify the stress-points where disappointment is likely to set in. That cough is pneumonia, you should go see a doctor; a delivery that is five minutes late won’t arrive unless you ring and complain; you should over-insure everything from your house to your health because the worst will almost certainly happen.

But while both Britons and New Yorkers expect things to be terrible, the latter believe outcomes can be changed, while the former, of course, subscribe to the “mustn’t grumble” school of disaster absorption to the point of getting weird satisfaction when their fears are confirmed. Oh, well, never mind, nothing to be done about it now, plough on, that’s the spirit, it’s probably for the best in the long run.

Viewed through this lens, Trump is the ultimate expression of American self-delusion, the glaringly obvious conman as king; while to American eyes, Brexit looks like an incomprehensible trudge towards the edge of a cliff, with every possible escape ignored. Brexit is mystifying to most Americans, period, but what is particularly incomprehensible is the slow-moving car crash and sense of inevitable doom of it all.

It has always been assumed that alarmism is what motivates New Yorkers to greater heights of efficiency than anyone in Europe can quite manage. But if at the core of all this is the question of how to be happy – if we allow that these efforts are, ultimately, in the service of that goal – then I still wonder which approach works the best. In New York, resignation is seen as a form of defeat, whereas I suspect that in Britain it reads as resilience. Which is the greater delusion: to believe you can micro-manage your way to a state of perfection, or that you can be content living alongside broken things?

On the British side, there is the martyrish snobbery of make-do-and-mend, a timidity masquerading as moral superiority. For New Yorkers, the daily battle to have things just as one wants them – whether that be the temperature of the room, or the precise components of one’s salad, which will be insisted on no matter how busy the deli – can feel like a kind of childish narcissism.

It did rain the next day, by the way, and there wasn’t anything to be done about it, although the prediction itself had been soothing. This is the one thing both cultures understand, I guess; there is always consolation in imagining the worst.

• Emma Brockes is a Guardian columnist