diff --git a/changelog.d/1350-cyclone-movement-knots.md b/changelog.d/1350-cyclone-movement-knots.md
new file mode 100644
index 000000000..3fc8c8f9f
--- /dev/null
+++ b/changelog.d/1350-cyclone-movement-knots.md
@@ -0,0 +1,3 @@
+- Convert NHC cyclone movement speed from miles per hour to knots, so
+  `movement.speedKt` in cyclone query results is no longer about 15% high
+  (rudycelekli, #1350).
diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index cf649e9f2..c8507dd72 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -417,6 +417,8 @@ than relabeling older geometry. The cone represents forecast center uncertainty,
 not storm size or the full hazard area. Successful empty and unavailable states
 are distinct. One owned native Cesium data source preserves polygon holes and
 geographic seams and releases on disable; forecast animation is not implied.
+NHC movement speed is converted from miles per hour to rounded knots by the
+proxy; advisory wind intensity is already in knots and is passed through.
 Cyclone markers, labels, tracks and cones are hidden beyond the horizon on every map source.
 Consult the linked official advisory for safety decisions.
 
diff --git a/server/providers/cyclones.js b/server/providers/cyclones.js
index 3e5f2f6d1..5aab0f246 100644
--- a/server/providers/cyclones.js
+++ b/server/providers/cyclones.js
@@ -43,6 +43,11 @@ function number(value, min, max) {
   const n = Number(value);
   return Number.isFinite(n) && n >= min && n <= max ? n : null;
 }
+// CurrentStorms.json reports movementSpeed in miles per hour (intensity is in
+// knots); convert so `speedKt` means what it says.
+function knotsFromMph(mph) {
+  return mph === null ? null : Math.round(mph * 0.868976);
+}
 // NHC stamps an advisory with its nominal time (e.g. 03:00Z) and publishes it
 // up to about half an hour before; allow that, but not a clock far ahead.
 const EARLY_ADVISORY_MS = 90 * 60_000;
@@ -120,7 +125,7 @@ export function parseCycloneStatus(payload, now = Date.now()) {
       pressureHpa: number(raw.pressure, 800, 1100),
       movement: {
         directionDegrees: number(raw.movementDir, 0, 360),
-        speedKt: number(raw.movementSpeed, 0, 200),
+        speedKt: knotsFromMph(number(raw.movementSpeed, 0, 200)),
       },
       advisoryUrl: officialLink(forecast.url),
       outlookUrl: raw.id.startsWith('al')
diff --git a/src/data/cyclonesProxy.test.mjs b/src/data/cyclonesProxy.test.mjs
index 23e84826c..6757f6e5c 100644
--- a/src/data/cyclonesProxy.test.mjs
+++ b/src/data/cyclonesProxy.test.mjs
@@ -115,7 +115,8 @@ test('status retains official clocks, knots, source links and finite current pos
   assert.equal(storm.issuedAt, TIME);
   assert.equal(storm.positionAt, TIME);
   assert.deepEqual(storm.position, { longitude: -125.8, latitude: 15.5 });
-  assert.deepEqual(storm.movement, { directionDegrees: 255, speedKt: 12 });
+  // NHC publishes movementSpeed in mph: 12 mph is 10 kt.
+  assert.deepEqual(storm.movement, { directionDegrees: 255, speedKt: 10 });
   assert.equal(storm.windKt, 25);
   assert.equal(storm.pressureHpa, 1006);
   assert.match(storm.advisoryUrl, /^https:\/\/www\.nhc\.noaa\.gov\/text\//);