Have you seen beautiful colors one day and the week they are gone? The challenge with foliage is it is very dependent on the weather (an excellent explanation here). Therefore, it is imperative to have an idea on what time of year is best for the area you want to see and then monitor daily or weekly reports from that area. There are tons of great resources out there for this in the North East.
North East Foliage Reports
In addition to visiting these websites, I encourage you to sign up for their newsletters / follow the different areas on Instagram so you don’t miss the updates!