This subject gets run up and down the flag pole several times a season
Go with your gut.
Mine have always come in at night, out in the daytime, 365 days/yr. Unless the weather is so horribly miserable, they stay in their stalls when I open their doors.
I also have 22 acres and an uncannily astute alpha horse. So astute I have watched him gather his herd in two different places, twice in the same day for two separate storms. And he was spot on both times.
I also worry about lightening but my horses can get hit by lightening easier than the barn can get hit. So far, over 9+ years, lightening has taken out 3 or 4 100 yr old oak trees right on the boundary lines
We're several hundred feet below the ridge, where most of those trees live, and the lightening seems happy to stay up there and cause mayhem --- so far-------------
According to the Weather Channel, my area is a "Tor Con Rating of 4" as I write this, and they're pretty sure that will go up as the day progresses. My horses are out and will stay out unless I see the alpha guy taking the others to the barn
After 22+ years of being my trusty trail horse and the lead horse in the pasture, I trust his judgment more than I trust most of the human population - lol lol