Hi.....Lava flow is not a seasonal thing, it happens as a result of geological shifts and the whim of Mother Nature. So if the volcano is erupting when you are there, that's just a bonus.

http://hvo.wr.usgs.gov/kilauea/update/main.html

is a fascinating site with daily updates on the lava flow. It seems a bit technical at first, but there is a lot there to absorb, even for a novice.

Based on what I've learned, lava flow is somewhat predictable depending on whether inflation is occuring. Inflation is the result of trapped lava and gases that pushes up the land. When it reaches its limit, it may explode with force! The more sedate lava flows are kind of like a drippping faucet; they may continue to flow, or they may gradually die down, or find a lava tube and change their point of exodus.

Unfortunately, it isn't predictable in the way you hope. At the moment, it is flowing less than hours walk from the turnaround at Chain of Craters road (almost on top of the old turnaround!) It could stop altogether or move to a location that requires several hours to hike to it or flow in such a way that it is never visible.

The kind of explosive eruption patg describes is much less likely than seeing Elvis on the beach. If you check the usgs web page as your trip gets closer you might be able to predict what you will find, but I don't think anyone can predict months from now.

I was afraid of that....oh well, at least I'll be in Hawaii, lava or not. thanks for the responses.

While no one can predict tomorrow let alone September, the current eruption has been going in some form or another for 20+ years.