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One knot (1 nautical mile per hour) is equal to 1.15 miles per hour so for forecasting purposes, a knot and a mile/hour can be used interchangeably. The criterion for a "correct" wind speed prediction can be adjusted by your instructor. For the MTEOR 206 course at Iowa State University, a value within + or - 5 knots of the reported wind speed is considered "correct".

On weather maps, the wind speed at a station is reported by a circle with a barb extending from it. The lines or flags attached to the tip of the barb report the wind speed at that station in knots. If there is one short line on the barb, this means the wind speed is 5 knots. If there is one long line, the wind speed is 10 knots. One long line and one short line stand for a wind of 15 knots, whereas two long lines stand for a wind of 20 knots and so on. A 50-knot wind is represented as a flag. If the wind is calm, no barb extends from the circle. Instead, a ring is shown around the circle. Click below to see examples of what the wind barbs look like.

Examples of Wind Speeds Winds                               Wind Help