Hello and welcome to planDisney, Peter. Time is of the essence and I can't help but think of the White Rabbit when it comes to all things related to time. We certainly don't want to be "late for a very important date."
The best place to check for park hours for your visit is at the
Hours & Events Calendar on the Disneyland site. Unfortunately, it looks like it's a bit too early to check for park hours for your upcoming visit. On average, you'll typically find information for dates as far out as 45 days (6 weeks) in advance. The good news is we're not late, just a tad early. I recommend coming back to check on the hours in the next few weeks or so.
While we don't have all of the information, there are some dates that we can be aware of for your upcoming visit. Because it will be
Halloween Time at the Disneyland Resort, there will be some nights when
Oogie Boogie Bash is taking place which will cause Disney California Adventure Park to close early. I checked the
list of dates in September and it looks like there will be parties on September 17th, 20th and 22nd. On each of these days, California Adventure will close early for this frighteningly fantastic event. For these dates, I recommend visiting Disneyland Park if you have a 1-Day, One Park Per Day ticket to pack in as much magic as you can. Or, if you have
Park Hopper tickets, you can hop over to Disneyland once California Adventure closes to extend the magic and finish out your day.
Peter, I'm sorry if this isn't the answer you were hoping for. While I wish I were all-knowing, like Madame Leota, I hope the information shared provides at least a peek behind the curtain to shed some light on some of your visit days. Please come back to see us with any other questions that you might have. Here's wishing you a ghoulishly good time at the Happiest Place on Earth. Say hello to the giant Mickey pumpkin for me and as you head down Main Street, U.S.A., turn around for a quick wink.
Michelle