Personally, I'd hold the fertilization until your next irrigation (or rainfall) and do it then instead.

I think you have a couple of options. If your grass isn't showing signs of needing nitrogen then you can hold off like morph suggested.

The other option is to apply it now and water a half an inch or so. If you search online for tips applying fertilizer, you'll see suggestions to fertilize when there is no rain in the forecast. That way you can control how much water it gets and you don't have to worry about getting a bunch of rain that may either wash the fertilizer away or cause it to leach through the soil. I used to apply fertilizer before a rain forecast but it either wouldn't rain or it would pour down to the point I would see puddles in parts of my yard. I would always be concerned about the leaching or washing away of fertilizer. Someone else will chime in and let you know if that is a legitimate concern or not because I honestly don't have a clue. Regardless for MY PEACE OF MIND, I fertilize when there's no rain in the forecast for a few days and I water it in.

I am with Sherm on this one. If the grass needs the nitrogen, apply and water half or 1/4 of your normal cycle. With my irrigation system, I would water for about 10-15 min. tops and it would be fine. For me to get an inch, I run about 30-45 min. depending on the area. If it does not show signs of needing the nitrogen, you can wait, but like Sherm said, they type of rain and how much you get is hard to predict.

Or if you are worried, just use organics and let it sit, until next rain fall :)

Thanks guys. The grass really doesn't need the nittogen, except for the bare spots where I killed the crab grass and dallis grass out. They are about half filled in and I'm trying like crazy to get them solid bermuda by the end of summer. I think I'll go ahead and put the nitrogen out and water it in with about 1/4". I think the moisture would help the runners spread as the top is dried out somewhat.

In those half filled in areas, I'd also be tempted to use an organic to arrange for a lower level of constantly-released nitrogen. When I get a patch, I heavily apply Milorganite, soy, or whatever's on-hand around it to encourage closure as fast as possible.

I've gotten trashcan-lid-sized holes to close in a single growing season using nothing more than judicious water and a lot of organics.

The reason for watering fertilizer in is to prevent burning. Burning is caused by the fertilizer dissolving into a small volume of morning dew instead of being dissolved with a lot more water. Does that help decide how much to water and when?