so funny, I was thinking just this the other day!
I was out and it was supposed to be headwinds, so I thought no big deal ride 12 miles north in 15+mph ne winds(so gusting in the 20s), turn around and be pushed home!
haha joke was on me, the headwinds changed to crosswinds! So I ended up going nowhere for 25 miles! it took me ages(i think I averaged around 15.5mph) There were definite times when my speed was around 13, and I felt like I was being blown backwards and sideways.
I am not sure when enough is enough, sometimes I look out at the palms just blowing sideways and say no way- not fun! don't want to be blown sideways into traffic, and then other days I am all gung(sp?)ho! for it..

I guess I would rather be riding out into a headwind then a tailwind(always more fun being blown home then vice versa)
Crosswinds above 15mph are just dangerous to me(I don't feel very safe being blown into the street when the cars already want to drive in the bike lane).

Also whoever said the hills make you strong wind makes you mean is right!
I would much rather have climbs, where you can see when it ends over winds where you can't see when it is going to let up.