Straight-Line Wind vs Microburst vs Tornado
By StormAuditor Editorial Team · Published 2026-10-06 · Updated 2026-10-07
Based on public NOAA and National Weather Service records, published under StormAuditor's methodology and data-source standards. Radar-derived hail sizes are estimates unless attributed to a ground report.
Damage-threshold ranges in this article are general guidance synthesized from industry and federal research — IBHS building-performance research, NWS severe criteria, and product standards such as UL 2218 (hail impact resistance) and ASTM D3161/D7158 (shingle wind ratings). Actual performance depends on product rating, age, installation quality, exposure, and impact characteristics — thresholds describe when damage becomes possible, not when it occurs.
Straight-line wind is any thunderstorm wind without rotation; a microburst is a small, short burst of it; a tornado is a rotating column touching the ground. On the ground, straight-line and microburst damage points one way or fans outward, while tornado damage converges and twists. NWS damage surveys use those patterns.
After a storm flattens fences and drops trees, the first question is often "was it a tornado?" Usually it was not. Most thunderstorm wind damage comes from straight-line winds, including downbursts and microbursts, and the National Weather Service tells the two apart from the damage pattern on the ground. This guide explains each type, how NWS surveys label them, and how to check the wind at your address on the storm date.
Straight-line wind, microburst, and tornado at a glance
| Straight-line wind | Microburst | Tornado | |
|---|---|---|---|
| What it is | Thunderstorm wind without rotation | A small, short downburst | Rotating column of air touching the ground |
| Size | Can cover miles to hundreds of miles | Outflow less than 2.5 miles wide | Usually a narrow path |
| Duration at one spot | Minutes | Peak winds under 5 minutes | Brief, as the vortex passes |
| Damage pattern | Parallel rows, one direction | Fans outward from a center | Converges and twists along a path |
| How NWS rates it | Estimated peak wind in mph | Estimated peak wind in mph | EF rating (EF0–EF5) |
Straight-line winds
The NWS glossary defines straight-line winds as "generally, any wind that is not associated with rotation, used mainly to differentiate them from tornadic winds" (NWS glossary). NWS Milwaukee/Sullivan notes that straight-line winds cause most of the wind damage from thunderstorms and leave debris such as uprooted trees "laid out in nearly parallel rows" (NWS).
Straight-line wind comes in several forms:
- Gust fronts: the leading edge of rain-cooled air spreading out from a storm.
- Downbursts: a strong downdraft from a thunderstorm that hits the ground and spreads out.
- Derechos: a widespread, long-lived windstorm from a line of storms. The Storm Prediction Center's criteria call for a wind damage swath at least 250 miles long, with gusts of at least 58 mph along its length and several, well-separated gusts of 75 mph or more (SPC: About Derechos).
Straight-line wind is not weak wind. NWS Milwaukee/Sullivan notes that downbursts can reach 100 to 150 mph.
Downbursts, microbursts, and macrobursts
A downburst is "a strong downdraft current of air from a cumulonimbus cloud, often associated with intense thunderstorms" (NWS glossary). The NWS splits downbursts by size:
- Microburst: "a convective downdraft with an affected outflow area of less than 2½ miles wide and peak winds lasting less than 5 minutes" (NWS glossary).
- Macroburst: an outflow at least 2½ miles wide with peak winds lasting 5 to 20 minutes (NWS glossary).
A wet microburst falls inside heavy rain. A dry microburst falls from a high-based storm with little rain at the ground, so the wind can seem to come from nowhere. Because a microburst is small, one block can be hit hard while the next street sees only rain. The microburst article covers how that damage looks on a property.
Tornadoes
The Storm Prediction Center defines a tornado as "a violently rotating column of air, in contact with the ground, pendant from a cumuliform cloud or underneath a cumuliform cloud" (SPC tornado FAQ). Tornado damage follows a path, and debris converges toward the center of that path or is twisted in different directions.
The NWS rates tornadoes after the fact on the Enhanced Fujita (EF) Scale, from the damage, not from a measured wind (SPC EF Scale):
| EF rating | Estimated 3-second gust |
|---|---|
| EF0 | 65–85 mph |
| EF1 | 86–110 mph |
| EF2 | 111–135 mph |
| EF3 | 136–165 mph |
| EF4 | 166–200 mph |
| EF5 | Over 200 mph |
Surveyors match what they see against 28 damage indicators, such as one- and two-family homes or hardwood trees, and a degree of damage for each. The EF Scale article explains the ratings in more detail.
How NWS damage surveys tell them apart
After significant wind damage, NWS meteorologists survey the area and publish their findings, often as a Public Information Statement on the local office's website. They look at:
- Direction of debris. Trees and debris in parallel rows, or fanning outward, point to straight-line wind or a downburst. Debris pointing inward or in crossing directions along a narrow path points to a tornado.
- Path shape. A tornado leaves a defined track with a start and end point. Straight-line damage is usually wider and less sharply bounded.
- Radar and reports. Rotation on radar, debris signatures, and spotter or video reports support a tornado finding.
- Degree of damage. The worst damage is matched to EF damage indicators to estimate the wind speed.
Survey results for straight-line wind usually give an estimated peak wind in mph, for example "estimated winds of 80 mph", without an EF rating. Strong straight-line winds can cause damage similar to an EF0 or EF1 tornado, which is why the pattern, not the severity, decides the label.
How to check the wind at your address on the storm date
Whatever hit, the wind at the property on that date is what goes into the record. To look it up:
- Check the estimated peak gust. The Free Report Snapshot answers YES or NO for an estimated gust of 45 mph or more (StormAuditor's screening threshold) at the address. A Wind Report lists the estimated peak gust for every storm date in the last two years.
- Look at the reports and warnings. The Storm Map shows storm reports, station peak gusts, and warnings by day. Local Storm Reports label events as thunderstorm wind damage, thunderstorm wind gusts, or tornadoes, with times and locations.
- See the whole swath. The Wind Explorer (Pro+ plans) maps estimated peak gusts statewide by date, which shows whether a narrow burst or a broad derecho-like swath crossed the area.
- Check the official record later. The NCEI Storm Events Database lists finalized "Thunderstorm Wind" and "Tornado" entries, usually a few months after the event.
The estimated peak gust is a value on a grid; a microburst or tornado core can be narrower than a grid cell. That is why the measured station gusts and the NWS survey sit next to the estimate.
Does the label matter for a claim?
For documentation, what matters most is the date, the wind the record supports at the address, and the damage pattern on the property. The label still helps: a survey finding of a tornado or a microburst explains why one property was hit hard when the neighborhood was not. Keep any NWS survey statement for your area with your photos and the weather record. The Wind Damage to Roof article lists what else to gather.
Frequently asked questions
What are straight-line winds?
Straight-line winds are thunderstorm winds without rotation. The NWS uses the term to separate them from tornadic winds. They include gust fronts, downbursts, microbursts, and derechos, and they cause most thunderstorm wind damage.
What is the difference between a microburst and a tornado?
A microburst is sinking air that hits the ground and spreads out over an area less than 2.5 miles wide. A tornado is a rotating column of air in contact with the ground. Microburst debris fans outward; tornado debris converges and twists along a path.
Can straight-line winds be as strong as a tornado?
Yes. NWS Milwaukee/Sullivan notes downbursts can reach 100 to 150 mph, and strong straight-line winds can cause damage similar to EF0 or EF1 tornadoes.
How does the NWS decide if damage was a tornado?
A damage survey looks at the debris pattern, the shape of the path, radar data, and reports. Convergent, twisted debris along a narrow path points to a tornado; parallel or outward debris points to straight-line wind.
Do straight-line winds get an EF rating?
No. The EF scale rates tornadoes. Straight-line wind surveys usually give an estimated peak wind speed in mph instead.
How do I find out what wind hit my house on a certain date?
Look up the estimated peak gust at your address for that date with a Wind Report, then check storm reports, station gusts, and warnings on the Storm Map. The local NWS office may also have published a damage survey.
Check the wind at your address with the Free Report Snapshot, or see every storm date with a Wind Report.