Sunday night/Monday morning August 12/13 is the peak of the annual and much beloved Perseid meteor shower. Meteor showers occur when the Earth gets to a point in its orbit crossed by the orbit of debris from a comet. Comets are basically big ol' chunks of rock and gravel held together by ice. When the comet gets near the Sun, the ice melts, and debris gets loose. Over time it spreads out along the orbit of the comet. If that orbit crosses ours, then we plow into the debris, which burns up in our atmosphere. Voila! Meteors!
Since this happens when the Earth goes past the intersection of the two orbits, it happens around the same time every year. The Perseids peak when the Earth passes through the debris left over from the comet Swift-Tuttle. The chunks are relatively dense in the debris field, so we get a lot of meteors, typically 60 or so per hour, maybe more. Only a couple of showers do better (the Geminids in December are good, for example) and since the Perseids peak in mid-August, they are a favorite for northern hemisphere folks.
Even better, there is a new moon this year, so the bright moonlight won't wash out faint meteors. You'll see more if you go out and look!
Important: because of the orbital geometry, the shower won't really pick up until after local midnight (literally, the halfway point between dusk and dawn). Going out right after sunset will just be disappointing. The later you stay up after midnight the better. Incidentally, the Perseids have a broad peak: you could go out as early as Friday night or late as Monday or Tuesday night and still see some.
A lot of people don't know how easy it is to watch a meteor shower, and think it takes a lot of prep. Nope! Here's a simple list of what you need.
1) A wide open sky with a view to the East
This is the biggest consideration. Meteors appear in random spots on the sky and can go from horizon to horizon. The more sky you can see, the more meteors you'll see. Try to avoid nearby buildings, trees, and so on.
If you trace the path of the meteors backward, they will appear to radiate from one point in the sky, located in the constellation Perseus (as played by Harry Hamlin). This is the same effect as when you're driving a car through a tunnel and the lights on the walls and ceiling appear to come from the point ahead of you. A good view of Perseus will again up the odds of seeing more meteors.
Perseus is in the east pretty much all night, so a clear eastward view is good. Being able to look in that direction will increase your odds of seeing more meteors. This isn't critical, though; just a big wide view is your best bet.
2) Dark skies
Meteors are generally not terribly bright. A few can be blazing, but most are about as bright as your average star, so you want to be away from lights. Your back yard might be fine, but make sure street lights are blocked and your house lights are off.
Once you're outside, it takes about 20 minutes for your eyes to get fully adapted to the dark -- your pupils dilate, letting in more light, and your eye produces a light-sensitive protein called rhodopsin. Both of these take time to fully kick in. So don't be disappointed if you see very few or no meteors right away. White light will bleach the rhodopsin, by the way, so if you need some light, use a flashlight with red cellophane covering the front. That will preserve your night vision.
4) A lounge chair
You need to be able to see a lot of the sky for minutes or hours, so you want to be comfortable. A chaise lounge or a folding beach recliner is a big plus. You can lie on the ground with a blanket if you want, but comfort is important if you're going to be out for a while. The ground tends to be cold at night, and wet, too. Which reminds me...
Yes, it's August, and in the northern hemisphere it can be hot, but temperatures drop at night. You won't be moving much, either, so you won't be generating much heat. 65 degrees Fahrenheit is cold if you're not moving. Also...
6) A hat
You lose most of your body heat through your head, so a hat helps a lot. [Updated: I've heard this factoid is not true, but still: a hat still keeps your head warm.] Plus, if you have a nearby street light, you can position your hat to block it. I've done that and it works! Added bonus: no mosquito bites on your head.
7) Telescope, binoculars
I recommend not using a telescope. Why not? Telescopes see only a small part of the sky, and meteors appear in random spots. I guarantee the best meteor of the night will happen while you are stooped over an eyepiece, and you'll miss it. However, Jupiter is well positioned for viewing, so this is as good a chance as any to do some observing, and I hate to tell people to not take advantage of a nice night! But be prepared to hear everyone else gasp and then mock you for missing the best meteor evah.
Binoculars are better. You can scan the sky, look for interesting things, and still be able to look around quickly if a bright meteor appears.
8) Star chart
Hey, you're outside! Why not get familiar with the sky? You can find charts at local bookstores, and online if you do a little searching. Sagittarius, Scorpius, Hercules... this is a fine time of year to be out looking for cosmic landmarks.
Oh boy, is this one important. It's after midnight, you're lying down, snuggled in a blanket, it's dark, and your eyes are focused on infinity. You start daydreaming a bit... and the next thing you know, the Sun is rising and you're covered in mosquito bites.
Take a nap Sunday afternoon.
10) Friends, family, neighbors
Having other folks with you will help you stay awake, and honestly, the joy and beauty of a meteor shower is best shared. One of my favorite times ever with The Little Astronomer was watching the Leonids shower years ago. She had a blast, and not just because she got to stay up until 3:00 a.m. with her dad... but then again, that's a big part of it, too.
11) An appreciation of what you are seeing.
Read up on meteor showers, what they are, what we've learned from them. Comets orbit the Sun for billions of years, and you're seeing tiny parts of them -- most no bigger than a grain of sand -- as they slam into our atmosphere a hundred miles away at speeds of up to 40 miles per second. How cool is that?
This may be the best thing to bring, and the easiest. Meteor showers are simply wonderful. It's a cosmic show, and it's free, and it's very, very cool.