OldLefty wrote:
Three important factors for casting into wind: trajectory, line speed and tight loop. For headwind, trajectory is up for backcast and down for forward cast. This has the loop straightening just before fly contacts water so it's exposed to the effects of the wind for the least amount of time.
For tailwind, trajectory is opposite that for headwind. This way the wind lends a bit of assistance to carrying the fly on the forward cast.
For sidewind, keep the fly on the downwind side of your body. For a wind blowing into your casting arm side get the rod tip over the opposite shoulder. All that needs to be done to have the rod tip moving over the opposite shoulder is to point the elbow away from the body while casting. The other two options are to cast with the other hand or turn around and present on the backcast as was mentioned earlier.
Tried to keep this short and sweet.