If you don't open the window at all, then Henry's suggestion is the one I'd look into first 1) assuming the water is only from direct rain (and not run-off), 2) you want an inexpensive solution.
If you open the window, obviously putting a bubble over the well is not what you want to do. I have 2 window wells with bubbles over them. One has a pump in it because it was there when we bought the home 6 years ago. Once it filled with water (and at that time, there wasn't a bubble on it). I left it there, initially, thinking there was more to the 'situation' then I first thought. But since I've put the bubble on, the pump has come on only that one time when the well was bubble-less. (I'd know if it came on because the open-end of the pump line creates enough pressure to blow out the dirt around it.)
Anyway, the bubbles at the Home Centers are made of real flimsy plastic. I suggest you go to a Lumber Yard and check around for the hard bubbles. Maybe even a gravel yard or quarry office has them. If not, do ask. Do your measurements first (widest measurement of the well and longest measurement of the well.) I know there are 2 sizes. Now, I ALSO have a well that surrounds an air vent to my crawlspace. It, I can't put a bubble on because the crawlspace needs air. So, I built a sort-of 'roof' over it. Before that, direct rain would fill the well in about 2 minutes in a heavy rain. And were I live a heavy rain lasts 15-20 minutes! So I use to get quite a bit of water in the crawlspace. The roof is held up with an elaborate PVC concoction that I'll spare describing here. (It does have shingles on it!) So, you have a couple of options.
There are quite a few posts on french drains, crawlspaces, basements, and landscaping on the Forum that I (thanks Henry) and others (including Henry) have replied to. They may be of use depending on what your situation calls for. If you need more info, post up or e-mail directly. My best to you and hope this helps.