Use gusts, not just average wind
Average wind may look fine while gusts are strong enough to scatter ash, flare flames, or relocate paper plates. Gusts above about 28 mph deserve caution; above the high 30s, waiting is usually sensible.
What wind affects
Wind can cool the grill, make charcoal burn unevenly, push smoke into faces or houses, and make flames less predictable. It also turns lightweight gazebos into regrettable engineering projects.
If you have to hold the napkins down with a bowl, check the gusts before lighting.