“The grid” is not some massively and totally integrated entity that hovers overhead, suspended only by spindly and rusting towers, teetering there wildly until a rogue puff of wind blows the whole thing onto our heads. “The grid” as it pertains to electric power generation and distribution (and from now on I’ll drop the quotation marks) is a system of various generation stations, transmission lines, distribution points and local substations all connected mechanically and electrically. The grid goes down in various ways and forms and places every day of the week… somewhere. It ain’ no thang. Power poles are knocked over in vehicle collisions; transformers blow out due to age and accumulated damage from exposure to weather; power plants trip off-line because of faults that they’re susceptible to; all kinds of things happen in electro-mechanical world.
Circuit breakers kick in to isolate the damaged area/s, then the trouble is located, crews are sent to repair or replace the damaged infrastructure, circuit breakers closed again to reconnect the formerly damaged area, customers reconnected and powered up, and life goes on. Or the fault at the power plant is fixed, anything connected with the unexpected trip is cleared, and the plant is brought back online and powered up (or in the case of a longer term problem, a plant that was formerly run only in “standby” mode is spun up to full power – sometimes several such plants are spun up – and the lost power is made up that way, while the base load plant is repaired or replaced.
Sometimes the damage is more widespread, as when ice storms or early snowstorms or massive flooding causes widespread damage in an area, and hundreds of thousands to millions are left powerless for varying times while the damage is isolated and contained and enough crews can be rounded up from far enough away to make more and more extensive repairs over a wider geographical area. In those cases it’s still just a function of time and money (as always), as well as being certain that the causes of the damage are past (the crews don’t often go out en masse in the teeth of a blizzard or hurricane, for example), which can stretch out the time element.
But this is why circuit breakers, repair crews, standby power generation and other systems exist in the first place.
On the other hand… there are massive problems with the maintenance and replacement scheduling and plans for huge parts of the national grid, such as aging and overloaded trunk lines and aging and less-capable power plants and too much reliance on particular fuels, sometimes, which can be interrupted. And when those things fail, and the trunk line is down for a week or a month, or the supply of natural gas gets shut off, when you’re relying on more and more gas-fired plants to produce the power for large sections of the country… then it’s going to be dark and cold for awhile.