Why is that, you might ask?
We'll, we can send a big thank you card to the Pacific Ocean.
Water takes much longer to heat and cool than air does, so the ocean temperature varies between about 50 degrees in spring to about 58 degrees in autumn.
Thus, that has a tremendous moderating effect on our weather. The ~55 degree ocean temperature keeps us milder in the winter, and cooler in the summer.
That setup thwarts the heat waves and blizzards (when we do get heat waves/snow storms, it's because the air is flowing from the east/northeast and coming from inland areas and not the ocean.)
Thunderstorms/tornadoes are usually formed from areas experiencing large temperature extremes -- i.e. a cold front between maybe 60 degree weather on one side and 90 degree weather on the other. Again, the ocean keeps those extremes from happening around here.
We don't get hurricanes because you need water temperatures in the 78-85 degree range, and thus the ocean is too cold at our latitude.
Lowland flooding/flash flooding is usually caused when tropical-type thunderstorms dump extreme amounts of rain in a short period of time -- again, we don't get those intense thunderstorms.
The flooding we do get is when the mountain areas get extreme amounts of rain (as terrain can squeeze out extra moisture from clouds), plus when it's warm enough so it falls mostly as snow.
Of course, the Pacific Ocean is also responsible for the wet climate around here, and having no one living out to our west makes it more difficult to forecast the area, but I think most would take the trade off.