In the 'good old days' we used to look at a snapshot of recorded gusts 1 hr prior to time off gate and examine the trend, if decreasing over the hour , we'd use the highest reading, however if increasing we's factor it up by 5%. (simplified, as obviously other factors are considered, but that's the guts (or should that be gust?!) of it
Not foolproof by any means, but better than suck it and see.
Regards