Went to get a shower the other day and had no hot water.
The last time this had happened was in Alaska, on a morning with temps on the nippy side of 50° below zero. I was reasonably sure that wasn't applicable here with the temperature on the balmy side of 20° above zero.
Turned out the electric water heater (we're all-electric here, except for the propane fireplace) had given up. Fortunately we have a good working relationship with an independent local plumber and by day's end we had a new tank, 25% larger than the previous one (which had been adequate for a house with one less full bathroom than we have).
I'm under the impression the previous owners of this house contracted to have the downstairs bathroom added and didn't care to upgrade the water heater because it was still in fair shape at the time. But (I suspect) when they discovered the capacity shortfall they had a supplemental water heater added in the laundry room that, as far as we can tell, only serves the clothes washer's hot water tap.
A few years before we bought the house, they'd had a water heater failure too (this was disclosed at sale), and I think they chose not to upgrade then because with the supplemental heater they didn't need to.
Me, I'm thinking if we've got sufficient capacity now it might be worth looking into having the supplemental tank removed. Its location crowds our laundry equipment and the room could benefit from losing as much clutter as we can extract, just on general principles.
This wasn't the first water heater we've had to replace, but the other one -- a gas-powered tank at our previous house -- had failed from the bottom, sending a river of water out the garage and down the driveway. This one failed at the top, a far less messy way to go. Apparently the leakage had gone down into the workings and tripped the fuse inside the unit. Without tripping the circuit breaker in the master panel.
Hot showers are something I refuse to do without, even in summer.