Mild winter. They didn't die off in great numbers, and more importantly, neither did their prey species.

Recent extended hot temperatures have forced out thirsty house spiders looking for a drink. You may see more indoors moving in habitable space during the day.

Previous uniform, cool weather conditions outside may have favored successful outdoor reproduction (although I have not noticed more webbing when moving around outside).

Indoor & outdoor spiders are typically different species. House spiders captured and put out most likely become meals. Not a bad thing; however, it spoiled my altruistic illusion that I was doing the captured arachnid a favor.

As appointed spider-wrangler I take them out of doors when convenient. Otherwise they accompany the toilet's content. I've done enough crawling underground in manholes, drains and sewer to assure you that is a great spider habitat. Quite the opposite of heading to that big web in the sky...

Yes. It's because of all the damned flies and because the seasons transitioned smoothly & mildly (no big teases of hot-cold-hot-cold, and no terribly big freeze like we sometimes have), - all in all, encouraging the little 8-legged rotters to have successful egg hatchings this year...

or

*goes goth*
yeah,
all the damned flies
...Buzzing and circling our rotting corpse of a society as we spiral into self-inflicted technocoma.

/bummer

Three times in the past week I've had to remove a rather large spider from my bathtub. (I use a plastic cup and paper to capture him and toss him outside.)

I just want to know if it has ever been the same spider. If not, are they part of the same family? Are there 1000 siblings all waiting to take turns exploring my tub?

Ive noticed that too. Never had any in my apartment before - two of em in the last couple of days. Very strange. Really big ones too.

I can't speak to whether or not there are actually more spiders this year or not. Certainly with warm and dry weather spiders are more active and evident and so it may seem that there are more around. As creepy as they may be, just capture the occasional one that gets indoors and release them outside (an inverted glass and a piece of stiff paper works well). If that is not possible for you, do what you have to so you feel comfortable in your house (just don't use poisons). The point is that we are most likely better off having them around then what they are eating.