Do I need to bring a jacket?

Don't waste space on a small umbrella...if it rains go to a café or buy an umbrella for a couple of euros from the guys who were minutes ago selling sunglasses and fake brand name purses...A light jacket with a hood is good..I recently packed one to make sure it DIDN'T rain...because if i hadn't, it would have....

Yes. I was in Paris last August for 9 days. It was cool and rainy most of those days. I told my friend who accompanied me to bring lots of cool clothes, sundresses, capris etc. as "August can be so hot" . We each packed one pair of long pants and one lightweight jacket. We ended up buying more clothes we were cold and sick of wearing same long sleeved shirt each day.
Bring a light weight rain jacket( wind breaker type is fine) and a sweater for layering.

It can always rain, so I always bring a light weight (unlined) rain shell. I don't pack an umbrella but I've bought one or two when needed over the years and brought them home as souvenirs. Umbrellas are great when there is rain and no wind. If it's windy, small umbrellas take a beating and don't really keep you dry.

Just checked the weather and the one week forecasts for Rome, Paris, Provence and Nice. Upper 60s for the most part with lots of clouds and some rain some days. The same in London. Although the forecast for Rome was for cooiish weather, the one for Florence was for much hotter weather.

It seems that there is a cool/rainy front over lots of Europe at present which IMHO is more comfortable for touring than HOT!!!!!

I use www.weatherunderground.com and search the cities I wish to look at and SAVE them so every time I go back to the site I can instantly see the weather conditions and the forecast for a week.

Amy, no matter when I travel, I always bring a rain coat. you just never know when/where you will get caught in a rain storm. I also use this jacket at night when it gets a bit cooler.

Check your local REI for really nice lightweight/packable rain jackets if you don't own one now.

Just plan to carry the jacket on the plane to reduce the space it would take to pack it in your luggage. You can use the jacket on the airplane to keep yourself warm...it seems to always be a bit cool on that plane for 10-14 hours!

Thank you all very much. We plan to carry on our bags so we want to save the space where possible.

I would pack a small durable umbrella if possible. Sure you can buy one there, but if like my experience you get caught in a shower on the Champs Elysee and have to buy one there, you will pay a LOT for a very poor-quality one, that breaks soon after.
I have lugged a nice raincoat to Europe a couple of times and after I only wore it once, no longer will do this, unless the weather forecast shows heavy rains, every day.

I would not bring an umbrella - it's just one more thing to carry. Instead, a light/waterproof shell with a hood can kill (at least) two birds with one stone. :-) The one I'll be bringing folds up into it's own pocket.

Amy, like other posters, I bring a lightweight windbreaker/rain jacket with a hood that I bought at REI. What's key, is that this jacket can be smashed up into one of the pockets so that it is more compact and easy to carry with you while siteseeing. I know there aren't many (if any) REI's in the central valley, but maybe a Big 5 or other sporting goods store would have them. Also, some are waterproof (no rain can penetrate the material) while others are water resistant (these work good for a light drizzle). Have fun!