It's odd that people are saying that their travel insurance doesn't cover weather alerts.
Certainly outdoor events can get cover against being ruined by bad weather.
Perhaps there are insurance professionals on the forum who can comment.
It seems there is a demand for cover which wpuld give limited payouts for small premiums.
It could be an optional surcharge at the time of ticket purchase - so self-funding.
I am not an insurance professional but I do know a bit about financial services more generally.
Insurance companies are businesses attempting to make a profit. Their income is mostly premiums received, from which they have to pay out the claims and cover their expenses. The insurance companies will set the premiums according to their assessment of their financial exposure which is a product of the risk of the insured event happening and the financial impact if it does.
Outdoor events can get cover for needing to cancel an event because the insurance companies can make an assessment of the risk of cancellation, based on past weather data. The payout is likely to be fixed as part of the contract, so, if the insured event happens then the financial impact is known. The premium payments will be relatively big and the administration costs relatively small.
Now compare that with travel insurance for individuals. It would be lots of small claims with a high administration cost, and much more difficult to estimate the total financial exposure to any weather event. I suspect that any insurance companies that have looked at this have decided that, in order to cover their financial exposure, they would have to set the premiums so high that very few people would pay.