Yes, the drive from San Antonio up to Lost Maples is indeed gorgeous. I'm always taken aback by how beautiful it is when it's been awhile since we've made the trip up there!
That May visit to Lost Maples you speak of must have been splendid. The Hill Country, of which Vanderpool and
Lost Maples SNA are included, is always slightly cooler than San Antonio, but by May the weather can be creeping into heatwave territory. One early February a couple years back, I remember driving out to
Hill Country SNA only to realize it was still closed for hunting -- the temperature was over 95 degrees, and had fooled me into forgetting hunting season was (that year, at least) still in full swing!
I've experienced a couple misty, cool mornings at Lost Maples SNA like the one you describe and it does seem to experience that weather pattern fairly often...at least at certain times of year. I still need to camp there -- can't believe I haven't yet! I'm always jealous of the Boy Scout troops or backpacking couples I see when I'm there for a day hike... :yes: