I'm considering STP next year and would like to get some input from people who have done it before. What are the headwinds like? I seem to recall hearing something somewhere about how headwinds being "bad" but without any details. I've done LOTOJA a couple of times and am comfortable with 200+ mile distances, but I wouldn't want to do a course if there were a nasty headwind the entire way.

I did STP twice, but the last time I did it was 16 years ago. My memory is a bit fuzzy, but I didn't think the headwinds were that bad. Nothing I would call extreme. There are a sections where there isn't any tree cover and if the winds are blowing, they always seem to be headwinds. All in all, I don't think it's much different from normal Pacific Northwest riding.

The prevailing winds in that area in July are from north to south, the same direction as the ride. So if anything it's mostly a tailwind that you can expect on STP. I've done STP a few times, can't ever remember a headwind of any significance. Don't worry about it, it's not likely to be an issue (that's not to say it can't happen).

Two years ago we had a pretty good tailwind for the second half of the ride. I didn't ride it this year, but I believe they had mostly tailwinds again.

As Shifty says, northerlies are more common than southerlies that time of year, but either way wind is generally not a big factor around here in the summertime. Now if rain bothers you, that's a different story...

I did the one day STP this year and it was a nice tail wind on the first half and a head wind on the second half. The next day it rained so it was worth it. My first one day double century. Averaged 16.5 mph on a tandem. 18.5 mph for the first half. The headwind only effected us during the last 30 miles so it seemed.

One day riders had some headwinds past Centralia (the start of the second hundred), they were a pain, but not that big of a deal, especially if you were in a paceline and had shelter between pulls.

As others have stated, tailwinds are generally the norm on the STP, at least during the first 1/2. After crossing into Oregon, there are usually headwinds coming down the Columbia River, although not bad compared to the real winds experienced routinely by riders in other parts of the country. We are talking maybe around 6-11 mph.
This year the headwinds started early, maybe right after Chehalis. Again, they were not enough to make the ride miserable, but rather contribute to various things that made my 12 hour total time goal unreachable (did it in exactly 13 hours, riding solo 85% of the distance.)

If you've ridden LOTOJA, there is nothing about the STP (other than the number of bikes on the road) to worry about. There were head / quartering winds for about a 40-mile section of the ride this year, and if you weren't in a paceline, they were tedious, but not a major obstacle. The usual wind direction is from the north, and the usual wind direction for the 50-or so miles in Oregon is also a tailwind ... if it were a headwind, (and it has been a few years), it could be fierce, in th 15-25 mph range, and you would want be be in a paceline and not the front rider!

I've been biking for 6 months, am still way overweight, and did STP two-days, no paceline, no problem. Headwinds were noticeable in a couple of places, nothing horrid though.

Get a bent.

If rain is coming...headwind. Sunny and hot...tailwinds.

I did STP for the first time this year and like others have said, tailwind for the first half, pushed us along quite well then after Centralia (second half) head wind but not too strong. I've heard that this is fairly normal experience. If you're comfortable doing 200 miles then STP will not be a big issue for you, it's quite an easy route.