That's a good question - I lost a rain cover a few years back. I found a generic cover at Academy that fit my bag so that's what I used. The umbrella does sound like a good idea for a temporary fix :-)

Titleist makes a bag hood.  Works great, especially if you are walking.  Check in out in the accessories section.  

There are also other companies out there that make good rain hoods that will fit your bag.  

Thanks for the suggestion.  I'll giving Academy a try.  I looked at Golfsmith on lunch today and no luck there.  I was hoping to find the Titleist hood/towel, but no luck on that either.

Why don't you get the Titleist rain hood/towel?  It works great.  I used it last weekend.

I will likely order one.  I haven't been able to find one in a local golf shop.  

Keith,

i might be able to help you but I'm not quite sure which bag you have. Can you throw up a picture of your bag?

Hendy, thank you so much for your offer.  Here's a picture of my bag.  

Well Keith, you have the only Titleist bag I don't have. Sorry I couldn't help you out. I've never seem that type of carry bag from Titleist. 

No problem.  I appreciate your attempt.  As an update, Saturday morning I went to the course only to find that they decided to close it on account of the rain.  As Steve suggested I'll order the hood/towel. 

The Titleist Raion hood/Towel is a good one, but you might also look at the Seaforth Rain Hood. It's used by a lot of pros and it works great.

I like the Seaforth a lot. I lost the hood for my carry bag several years ago and could not find a replacement hood. I bought several of the hood towel combos. I didn't carry for them to big, didn't stay on as well. Resorted to keeping a couple of black 32 gallon trash bags in my bag. Not a very elegant solution but very effective.

I have a similar situation - I have a 9.5 inch staff bag and have been unable to find a 'factory' replacement bag hood / rain hood. Have been looking for some but have not had any luck. Any advice would be welcomed - Thanks in advance, guys.