Environmental sounds, or more specifically, rain and wind (and associated sounds like trees moving in the wind) seem to be to quiet at more severe rates.
The current volume is acceptable for wind speeds around 10 to 15 or lower, but volume should be scaled with wind speed/rain rate. At the top end, winds blowing or gusting at 100 km/h should create an almost deafening roar, especially compared to the current gentle fluttering of leaves.
turn your volume to a normal listening level, create a mission, and step through different wind speeds. Winds blowing at 100 km/h seem to have a decent intensity, but very low volume. Current volume levels DO offer a subtle hint that the wind is actually blowing, but are not at a level to make the environment immersive.
Scaling the sound levels of wind or rain based on speed/severity my be beyond the scope of the current sound engine, but would make the game much more immersive and provide an element of gameplay not normally experienced in other games.. Imagine trying to hear your squad leader shout orders on a calm day. You hear him very clearly. Now, imagine trying to hear him in a thunderstorm with high winds and heavy rain. Currently, you hear him the same as on a calm day. What about vehicles? Did you hear that OPFOR vehicle roll past your position at about 100 meters? Of course you did! BUT, would you hear it during a heavy rain, or thunderstorm?