Memorial Day weekend is one of the busier weekends during the summer months both for the National Park and National Forest. The Park will be open this weekend, but typically the Sequoia National Forest offices are not. However, the Western Divide Ranger District office and the Kern River Ranger District Lake Isabella office will be open this Saturday, May 25, from 8 AM to 4:30 PM.
If you need information, obtain permits, or buy books/gear, the doors will be open. If you are wanting to get a head start on securing that special spot in the wilderness this weekend, I would try to get what you need done Friday. This way you can get an earlier start on Saturday morning. Otherwise you will have to wait till 8 AM to get your permit.
The weather is going to be cooler than normal, so check out the weather section to plan accordingly. Remember there are no camp fires allowed in the wilderness per Forest wide fire restrictions! You can use your stoves to cook your food though.