You usually have to buy it withing a limited amount of time from booking, precisely for this reason. Insurance companies don't want to sell insurance when the known risk has changed. Or, avoid insurances and pay a little more for refundable flights. Most hotels let you cancel without penalty within a day or two of your scheduled arrival; few other expenses would normally be prepaid or nonrefundable unless you're on a cruise or a group tour.

Yes. Does your credit card have trip insurance? Did you prepay your hotel or car rental? Did you book basic economy flights?

Is it too late to buy trip insurance for a trip to Florida next weekend? Looks like another storm is brewing.