This might be a "duh" question quot;>, but here goes:
Since it stays light for so long, when is it that the temperature usually starts to drop for the evening up in the Rockies?
I would think that it was once the sun went down, so that it would stay "warmer" until close to 9:30 at night. But as I'm in the process of packing =D>, it would be helpful to have that confirmed.

IF it has been a warm day, then it can stay warm till quite late. I don't know till what time, say 9.00 p.m. or 9.30 p.m. The exact time depends on where you're located and whether or not there is a mountain shading the spot in which you're located once the sun gets lower in the sky. But all this is relevant only if it's been a warm day.

The thing is, though, that the weather in the mountains is very changeable. So some days, or parts of some days, can be cool. In that case, the question of when the weather will start to drop for the evening may be academic, since the temperature hardly may have risen all day.

You pretty much have to pack layers, and you have to be prepared to wear anything from a short sleeved T-shirt through a fleece jacket topped by a water resistant shell at any time.

Even if the weather is good when you set out for a drive, you need to bring everyone's jacket with you in your car. When you set out for a hike, everyone needs to bring a jacket too. People have different ways of doing this. Some people carry day packs on their backs and store their jackets in the packs. Other people tie their jackets around their waists.

I recommend that a family have a couple of day packs, as they're useful for carrying so many things besides jackets (wallets, keys, a bottle of water, etc.)

Actually hibuscushouse - this is a very good question and not "duh" by any means.

Although at this latitude the sun rises early and sets very late, the arc it circumscribes in the sky means that it rises far to the northeast, is high to the south at true mid-day (which because of daylight time and time zones is not at noon), and then it sets far to the northwest. If there was a line in the sky which displayed this arc, you would see that the sun stays fairly low for a long time during rising and setting, and at this low phase the sun's rays have to get through a lot of atmosphere before getting to the ground, so they don't provide the warming that they do at mid-day.

Another reason that it cools quickly in the mountains is that at higher elevations the air is thinner, and isn't able to retain heat for the same length of time as more dense air at low elevations.

When I'm in the mountains during hot summer days I usually wear shorts and a T-shirt; if we are hiking I will wear shorts, T-shirt and hiking boots (with socks!!), and I take along a waterproof shell just in case it rains. I've never found the need to take along a sweater or fleece jacket (I generate enough heat just by hiking!!!).

However, in the evening when the sun's rays are low and it starts to cool down and you are sitting at an outdoor cafe doing nothing more strenuous than sipping a cappucino, you will feel chilly quickly and it's a good idea to have a sweater or light fleece jacket with you.

how do you do that clapping smiley thing???

Try:

http://www.fodors.com/forums/smileys/

Hibiscushouse, I hope I'm in time to catch you before you leave. I'm glad Borealis explained the technical stuff about the sun's arc.

I had a chance to run a test last night. Yesterday was a sunny day in Calgary, and the temperature reached a high of 74.8 deg F. Last night we sat in our back yard and had a barbeque. We were wearing short sleeved shirts. Although the sun was still shining, I found I had to come in and get a sweater around 8.00 p.m.

Calgary is about 3,500 feet above sea level. Banff is about another 1,000 feet higher than that, and Lake Louise is a bit higher still. I don't know the elevation in the places in which you'll be vacationing. But added elevation will tend to make things a couple of degrees cooler.

Sorry, guys, but I just have to test this smiley thing. I've never done them.

Wow! Not the one I tried to do, but I get the picture.
Thanks for the site. They are so cute.
Have a good trip Hibiscushouse. We are going to the Rockies in August, so this info helps us too.

I don't leave until the morning. 8-)
Thank you, both, for your helpful information. It's been so warm here for several months now, so it's hard to remember what it feels like to be in chilly or cold weather. But if you went in for a sweater, Judy, I'm sure I would have had to go in to get a jacket!

I think we're set though, having packed a little bit of this and a little bit of that. At least I hope we're set.

Thank you all for helping us plan our trip. You've been a terribly valuable resource, going above and beyond with your answers, and it's very much appreciated! ><
If you see us walking around your town, stop us and say hello. We'll be easy to spot; 3 young boys, grandparents, a couple of college kids, and 4 middle age parents all with our Tampa Bay Stanley Cup t-shirts on.

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