I would wait until it turns green. The grass can't use fertilizer when it's not growing and fertilizer stresses grass if it's hot out.

For the last application, wait until the grass has stopped growing but while it is still green. I pay more attention to the grass and less attention to the calendar. The grass is a better indicator of the right time to fertilize.

Just a slight distinction here: the grass is brown from lack of water. Your are limiting yourself to rain instead of irrigating. I'm just quibbling; don't mean to start anything, but some people are absolutely flabbergasted that lawns cannot always survive on rain.

There are a couple solutions to that problem. I choose to irrigate my lawn weekly to keep it green. bpgreen chooses grass types adapted to arid climates so he does not have to irrigate. If you want to save the water, you could look into using native and prairie type grasses. When you get enough of them (density) and mow them, they look like everyone else's lawn. Those grasses have the additional benefit of not needing much fertilizer.

David, I think you're projecting a bit. Conditions in the midwest are very different from what you and I see.

I used to live in the midwest and turfgrasses like KBG can stay green for most of the year with no irrigation and can stay green all year if you use a sprinkler a few times when the afternoon rains don't come. If it isn't watered, it'll likely go dormant for a few weeks.

In a drought year, with no additional water, the lawn will likely go dormant for a month or so. Tall fescue will stay green longer than KBG, but once it goes dormant, it goes dead in a hurry. KBG will go dormant faster, but will snap back once the rains start unless the drought was extreme.

Keep in mind that what would be considered a severe drought in the upper midwest would be viewed as an unusually wet year for either of us.

It was late. I should have said that the OP could fix the brown by irrigating. Call it a trick to get back onto the calendar schedule. When the grass greens up from the water, then fertilize.