Crosswind Component Estimation

From FlightSim

• If the crosswind is 15º off of the runway heading, the crosswind component is about 1/4 of the wind velocity, while the head/tail-wind is about 19/20 of the wind velocity, or essentially all of it. So with a 20 knot wind at 15º off the runway heading, you'll still have about 20 knots headwind with about a 5 knot crosswind component.
• With a 30º crosswind, it's 1/2 and 9/10, for about a 10 knot crosswind component and a 20 knot head/tail wind component for that same 20 knot wind.
• At a 45º crosswind angle, it's 2/3 and 2/3, so that same 20 knot wind would give you 15 knots on the nose/tail and 15 knots crosswind component.
• Much beyond a 45º angle, you'd just as well figure the entire wind value as crosswind component, with decreasing head/tail wind as the angle increases.

Using the values above will give you a quick way to approximate the effects of crosswinds and, while they won't always result in exact amounts, they will give you an idea of what you have to deal with.