WEATHER TOOLS

Weather Calculators

Maritime weather calculators for wind, waves, swell, visibility, dew point and tropical cyclone avoidance.

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WMOStandards-based

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Beaufort Scale Estimator

Convert between Beaufort number, wind speed in knots, m/s and km/h

Wind

V (kn) ≈ 1.625 × B^1.5 | B = (V ÷ 1.625)^(2/3)

Beaufort Number (0–12)Wind Speed (kn/m/s)

Wave Height from Wind

Estimate significant wave height from sustained wind speed and fetch

Waves

H_s ≈ 0.0248 × V² (simplified) | Bretschneider method for fetch-limited

Wind Speed (kn)Fetch (NM)Duration (hrs)

Humidity & Dew Point

Calculate relative humidity, dew point temperature and apparent temperature

Atmosphere

T_dp = 243.04 × [ln(RH/100) + 17.625T/(243.04+T)] ÷ [17.625 − ...]

Dry Bulb Temp (°C)Wet Bulb Temp (°C)Relative Humidity (%)

Visibility Estimation

Estimate meteorological visibility from atmospheric conditions and observations

Visibility

Meteorological Optical Range (MOR) per WMO scale

Observable Distance (NM)Light Source IntensityAtmospheric Conditions

Swell Period / Length

Calculate swell wave period, wave length and wave speed from observed conditions

Swell

L = g × T² ÷ (2π) | C = g × T ÷ (2π) where T is period in seconds

Wave Period (s)Wave Height (m)Water Depth (m)

Wind Speed Converter

Convert wind speed between knots, m/s, km/h, mph and Beaufort scale

Conversion

1 kn = 1.852 km/h = 0.5144 m/s = 1.151 mph

Wind SpeedFrom UnitTo Unit

Cyclone Track Prediction

Calculate predicted position of tropical cyclone using track and intensity data

Cyclone

Predicted Pos = Current Pos + (Track Speed × Time × sin/cos(Track Direction))

Current Position (Lat/Lon)Track Speed (kn)Track Direction (°)Time (hrs)

Safe Passing Distance from TC

Calculate minimum safe passing distance from tropical cyclone for vessel routing

Cyclone

Safe Distance ≥ Radius of 34-kt winds + Vessel Speed × 24hr margin

TC CategoryGale Force Radius (NM)Vessel Speed (kn)TC Speed (kn)

About Weather Calculators

These weather calculators assist mariners in weather analysis and voyage planning. They follow WMO standards and IMO guidelines for meteorological observations at sea. For official weather routing, always consult the vessel's designated weather routing service and the relevant meteorological authority NAVTEX/METAREA broadcasts.