this may be considered controversial

but one should slow to the computed Va [based on weight/stall speed] if severe gusts are really encountered ---don't worry about the stall you wont exceed design limit loading and if equipped/necessary you'll have stick pusher protection or the stall would be a better option than structural failure: so if really caught out;
slow way way down and remember that since maximal wing loading i.e. weight to surface area loading occurs at the stall
Va will thus be dependent on Vs [as previously described by Keith Williams]
and Vs is a function of weight the
Higher the Vs the Higher the Va will be hence you will have a Higher Va at a Heavier weights,...FAR 25 is comprehensive but there are several large Gaps that can kill those caught unaware of the limitations of the design envelope
Actually, the whole picture is quite complex
PA