WMO STORM SCALE STANDARDS
Typhoon & Hurricane Wind Scale Converter
Global Storm Category Standard Comparison Matrix
SSHS
CMA
JMA
BOM
HKO
PAGASA
IMD
MFR
FMS🛡️ Hazard Impact
Walking
Hard to Stand
Driving
Truck Flip Risk
Trees
Trees Uprooted
Structures
Roofs Blown Off
Converter Features
Real-time Multi-unit Sync
Drag the slider to convert wind speeds instantly between m/s, km/h, knots (kts), and mph with 0.1-level precision.
Global Official Scales Align
Supports cross-comparison between SSHS, CMA, JMA, HKO, PAGASA, and IMD official standards.
Dynamic Impact Assessments
Built-in impact engine translates abstract wind speed values into intuitive real-life hazard severity ratings.
Wind Scale & Typhoon Category FAQ
Why do US agencies (NHC/JTWC) report higher wind speeds for the same hurricane than JMA or WMO?
US warning centers (NHC and JTWC) base storm categories on a 1-minute sustained wind average, which captures brief peak velocities. Agencies like JMA and BOM use a 10-minute average that smooths out extreme fluctuations. As a result, 1-minute values are numerically about 14% higher than 10-minute values.
How do I convert between Knots (kts), Miles per Hour (mph), and Meters per Second (m/s)?
1 knot equals 1.15078 mph and 0.51444 m/s. For instance, Category 1 hurricane threshold is 64 knots, which converts to 74 mph or ~33 m/s. Use our converter slider above to convert all 4 major units instantly.
What is the difference between Sustained Winds and Peak Gusts?
Sustained winds measure the continuous average velocity over a designated time window (1-min or 10-min) and dictate official category classifications. Peak gusts are sudden, short-duration (3-second) bursts of wind that are typically 20% to 50% stronger than sustained winds.
The Science of Measurement
Why do JTWC wind speeds always seem higher than JMA's? It all comes down to 'averaging time'. Shorter times capture higher, extreme gusts.
The Physics Behind the Formulas
Why shorter averaging times mean higher values?
Wind in nature is not constant; it fluctuates with gusts and lulls. A shorter averaging time (like the US 1-minute standard) captures short, extreme gust peaks. A longer averaging time (like the WMO 10-minute standard) smooths out these fluctuations, resulting in a lower, more stable average value.
The Origin of 1.14 and 1.06
These are not theoretical derivations, but empirical constants derived by meteorologists through decades of marine observations (e.g., WMO 2010 Guidelines for converting wind averaging periods). It is internationally recognized that 10-minute sustained winds are roughly 88% of 1-minute winds (1 ÷ 0.88 ≈ 1.14), while 2-minute winds are roughly 94% of 1-minute winds (1 ÷ 0.94 ≈ 1.06).
Real-time Wind Sync
Avoid manual calculation formulas. Convert instantly between 1-min, 2-min, and 10-min averages.
Official Scales & Alert Colors
Beyond just wind speeds, it dynamically displays exclusive official terminology (e.g., severe tropical storm, super typhoon).
Realistic Damage Mapping
Translates abstract wind speeds into intuitive physical damage simulations and severity levels.