The months I try to travel are May, or September. I've previously read that Sept. could be good, but now I am wondering about May as an option.

September is likely to be better than
May - May more inclined to rain and cool weather -

It's iffy.

I'm a native Oregonian and I can tell you that most of the time the coast is overcast and windy. During fall-spring it's rainy too. Even during the summer it's challenging to have a really warm day at the beach with not a lot of wind. Probably August would be best since lately it hasn't heated up here until end of July/August. Basically, plan on the weather being in the 60's in Sept, and 50's or 60's in May--with WIND--which makes it feel a lot colder. Dress warm. Coat and long pants--just in case. But again, you never truly know how it will be until the day of. It's a little unpredictable. But the beaches are beautiful and well worth the trip. Canon Beach is great. Hope that helps!!
--Noyes
PS Remember, the water is REALLY cold--most people don't venture in!

I have heard that Oregonians do not swim or surf in the ocean...I was there in Sept and it was quite chilly & windy. But it is great for walking on the beach and eating clam chowder at Mo's
Too bad you are not here today- warm and sunny! Beach weather I betcha!

I live on the coast...spring and fall are the best months to do the coast!

In summer there is usually a marine layer that burns off by mid to late afternoon.

In spring and fall...it can be sunny all day long!

I am an Oregonian as well and lived on the coast for 10 years (Coos Bay) I will only say that the weather doesnt change much year round. Less rain in the summer for sure but when traveling here one should be prepared for rain at all times. I live in Grants Pass now and have family on the coast still. I will often call over there and tell them how warm and clear it is in the valley only to find out its pouring over there. Temp wise...even in the summer I would say have a sweater or something handy. If your coming from a warm climate to the coast you may find their idea of warm and yours are two diffent things! Two things sum up weather here year round...Oregonians dont tan....we rust. If you dont like the weather in Oregon...give it five minutes. BTW it is beautiful year round though I prefer Sept. to May.