nws-weather-mcp-server

Nws Get Forecast

nws_get_forecast

Read-only

Get the weather forecast for a US location. Returns either named 12-hour periods (default) or hourly breakdowns.

Input Schema

TableJSON Schema

Name	Required	Description
`cursor`	No	Opaque continuation token from a previous response's nextCursor, to retrieve the next 48 periods. Omit for the first page. Every call re-fetches the forecast, so consecutive periods are contiguous within one response; NWS reissues forecasts through the day, so a later call can window a regenerated period array.
`hourly`	No	If true, returns hourly forecast (48 one-hour periods per page, ~156 available) instead of 12-hour named periods (14 periods). Hourly includes dewpoint and relative humidity.
`latitude`	Yes	Latitude in decimal degrees (e.g., 47.6062).
`longitude`	Yes	Longitude in decimal degrees (e.g., -122.3321).

Output Schema

TableJSON Schema

Name	Required	Description
`mode`	No	Forecast mode: "hourly" or "7-day"
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Number of forecast periods in this page (at most 48).
`notice`	No	Set when periods remain beyond this page, or when the supplied cursor points past the end of the period array.
`periods`	No	Forecast periods
`location`	No	Resolved location metadata
`nextCursor`	No	Opaque token for the next page of periods — pass it back as `cursor`. Omitted when this is the last page.
`totalCount`	No	Total forecast periods available upstream before the page window was applied — NOT the number in this page, which is shown. Compare it against shown to tell whether periods were withheld.
`generatedAt`	No	When the forecast was generated (ISO 8601)

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 30, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage. `marine_forecast_unsupported`: Coordinates fall in a marine area, where NWS publishes no point forecast. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage. `marine_forecast_unsupported`: Coordinates fall in a marine area, where NWS publishes no point forecast. `no_forecast_grid`: Coordinates are on land in a forecast zone NWS serves no forecast grid for (e.g., interior Northern Mariana Islands). Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "out_of_scope",
-  "marine_forecast_unsupported"
-]New value: +[
+  "out_of_scope",
+  "marine_forecast_unsupported",
+  "no_forecast_grid"
+]

Changed2 schema fields changedSep 25, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage. `marine_forecast_unsupported`: Coordinates fall in a marine area, where NWS publishes no point forecast. Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "out_of_scope"
-]New value: +[
+  "out_of_scope",
+  "marine_forecast_unsupported"
+]

Changed1 schema field changedSep 19, 2026

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage. Other values are possible when a failure originates below the handler."

Changed6 schema fields changedSep 4, 2026
- removedOutput schema / properties / periods / items / properties / dewpointC / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / periods / items / properties / dewpointC / type
```
Added value: +[
+  "number",
+  "null"
+]
```
- removedOutput schema / properties / periods / items / properties / precipChancePct / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / periods / items / properties / precipChancePct / type
```
Added value: +[
+  "number",
+  "null"
+]
```
- removedOutput schema / properties / periods / items / properties / relativeHumidityPct / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / periods / items / properties / relativeHumidityPct / type
```
Added value: +[
+  "number",
+  "null"
+]
```

Changed6 schema fields changedAug 25, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "location",
+      "generatedAt",
+      "periods",
+      "totalCount",
+      "shown",
+      "mode"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `out_of_scope`: Coordinates fall outside US National Weather Service coverage Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "out_of_scope"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "location",
-  "generatedAt",
-  "periods",
-  "totalCount",
-  "shown",
-  "mode"
-]

Changed5 schema fields changedAug 13, 2026

removedOutput schema / properties / periodCount

Removed value: -{
-  "description": "Number of forecast periods in this page (at most 48).",
-  "type": "number"
-}

addedOutput schema / properties / shown

Added value: +{
+  "description": "Number of forecast periods in this page (at most 48).",
+  "type": "number"
+}

addedOutput schema / properties / totalCount

Added value: +{
+  "description": "Total forecast periods available upstream before the page window was applied — NOT the number in this page, which is shown. Compare it against shown to tell whether periods were withheld.",
+  "type": "number"
+}

removedOutput schema / properties / totalPeriodCount

Removed value: -{
-  "description": "Total forecast periods available upstream before the page window was applied.",
-  "type": "number"
-}

changedOutput schema / required

Previous value: -[
-  "location",
-  "generatedAt",
-  "periods",
-  "periodCount",
-  "totalPeriodCount",
-  "mode"
-]New value: +[
+  "location",
+  "generatedAt",
+  "periods",
+  "totalCount",
+  "shown",
+  "mode"
+]

Changed6 schema fields changedAug 13, 2026

addedInput schema / properties / cursor

Added value: +{
+  "description": "Opaque continuation token from a previous response's nextCursor, to retrieve the next 48 periods. Omit for the first page. Every call re-fetches the forecast, so consecutive periods are contiguous within one response; NWS reissues forecasts through the day, so a later call can window a regenerated period array.",
+  "type": "string"
+}

changedInput schema / properties / hourly / description

Previous value: -"If true, returns hourly forecast (next 48 one-hour periods) instead of 12-hour named periods (14 periods). Hourly includes dewpoint and relative humidity."New value: +"If true, returns hourly forecast (48 one-hour periods per page, ~156 available) instead of 12-hour named periods (14 periods). Hourly includes dewpoint and relative humidity."

addedOutput schema / properties / nextCursor

Added value: +{
+  "description": "Opaque token for the next page of periods — pass it back as `cursor`. Omitted when this is the last page.",
+  "type": "string"
+}

changedOutput schema / properties / notice / description

Previous value: -"Set when upstream returned more periods than the cap — states how many periods were omitted."New value: +"Set when periods remain beyond this page, or when the supplied cursor points past the end of the period array."

changedOutput schema / properties / periodCount / description

Previous value: -"Number of forecast periods returned (capped at 48)."New value: +"Number of forecast periods in this page (at most 48)."

changedOutput schema / properties / totalPeriodCount / description

Previous value: -"Total forecast periods available upstream before the cap was applied."New value: +"Total forecast periods available upstream before the page window was applied."

Changed5 schema fields changedJul 2, 2026

changedInput schema / properties / hourly / description

Previous value: -"If true, returns hourly forecast (~156 periods) instead of 12-hour named periods (14 periods). Hourly includes dewpoint and relative humidity."New value: +"If true, returns hourly forecast (next 48 one-hour periods) instead of 12-hour named periods (14 periods). Hourly includes dewpoint and relative humidity."

addedOutput schema / properties / notice

Added value: +{
+  "description": "Set when upstream returned more periods than the cap — states how many periods were omitted.",
+  "type": "string"
+}

changedOutput schema / properties / periodCount / description

Previous value: -"Number of forecast periods returned"New value: +"Number of forecast periods returned (capped at 48)."

addedOutput schema / properties / totalPeriodCount

Added value: +{
+  "description": "Total forecast periods available upstream before the cap was applied.",
+  "type": "number"
+}

changedOutput schema / required

Previous value: -[
-  "location",
-  "generatedAt",
-  "periods",
-  "periodCount",
-  "mode"
-]New value: +[
+  "location",
+  "generatedAt",
+  "periods",
+  "periodCount",
+  "totalPeriodCount",
+  "mode"
+]

Changed2 schema fields changedJul 1, 2026

changedInput schema / properties / latitude / description

Previous value: -"Latitude in decimal degrees (e.g., 47.6062). Truncated to 4 decimal places."New value: +"Latitude in decimal degrees (e.g., 47.6062)."

changedInput schema / properties / longitude / description

Previous value: -"Longitude in decimal degrees (e.g., -122.3321). Truncated to 4 decimal places."New value: +"Longitude in decimal degrees (e.g., -122.3321)."

Changed3 schema fields changedMay 30, 2026

addedOutput schema / properties / mode

Added value: +{
+  "description": "Forecast mode: \"hourly\" or \"7-day\"",
+  "type": "string"
+}

addedOutput schema / properties / periodCount

Added value: +{
+  "description": "Number of forecast periods returned",
+  "type": "number"
+}

changedOutput schema / required

Previous value: -[
-  "location",
-  "generatedAt",
-  "periods"
-]New value: +[
+  "location",
+  "generatedAt",
+  "periods",
+  "periodCount",
+  "mode"
+]

Changed7 schema fields changedMay 16, 2026

removedOutput schema / properties / periods / items / properties / dewpoint

Removed value: -{
-  "anyOf": [
-    {
-      "type": "number"
-    },
-    {
-      "type": "null"
-    }
-  ],
-  "description": "Dewpoint in Celsius (hourly only)"
-}

addedOutput schema / properties / periods / items / properties / dewpointC

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Dewpoint in Celsius (hourly only)"
+}

removedOutput schema / properties / periods / items / properties / precipChance

Removed value: -{
-  "anyOf": [
-    {
-      "type": "number"
-    },
-    {
-      "type": "null"
-    }
-  ],
-  "description": "Probability of precipitation (%)"
-}

addedOutput schema / properties / periods / items / properties / precipChancePct

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Probability of precipitation in percent (0-100)"
+}

removedOutput schema / properties / periods / items / properties / relativeHumidity

Removed value: -{
-  "anyOf": [
-    {
-      "type": "number"
-    },
-    {
-      "type": "null"
-    }
-  ],
-  "description": "Relative humidity % (hourly only)"
-}

addedOutput schema / properties / periods / items / properties / relativeHumidityPct

Added value: +{
+  "anyOf": [
+    {
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Relative humidity in percent (0-100, hourly only)"
+}

changedOutput schema / properties / periods / items / required

Previous value: -[
-  "name",
-  "startTime",
-  "endTime",
-  "temperature",
-  "temperatureUnit",
-  "windSpeed",
-  "windDirection",
-  "shortForecast",
-  "detailedForecast",
-  "precipChance",
-  "dewpoint",
-  "relativeHumidity"
-]New value: +[
+  "name",
+  "startTime",
+  "endTime",
+  "temperature",
+  "temperatureUnit",
+  "windSpeed",
+  "windDirection",
+  "shortForecast",
+  "detailedForecast",
+  "precipChancePct",
+  "dewpointC",
+  "relativeHumidityPct"
+]

Changed1 schema field changedApr 24, 2026
- addedOutput schema / properties / periods / items / description
```
Added value: +"Single forecast period with time range, conditions, and narrative"
```

Changed3 schema fields changedApr 14, 2026

addedOutput schema / properties / location / properties / county

Added value: +{
+  "description": "County zone code for chaining to nws_search_alerts",
+  "type": "string"
+}

addedOutput schema / properties / location / properties / forecastZone

Added value: +{
+  "description": "Forecast zone code for chaining to nws_search_alerts",
+  "type": "string"
+}

changedOutput schema / properties / location / required

Previous value: -[
-  "city",
-  "state",
-  "office",
-  "timeZone"
-]New value: +[
+  "city",
+  "state",
+  "office",
+  "timeZone",
+  "forecastZone",
+  "county"
+]

First observedApr 13, 2026

TDQS

B3.2/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

readOnlyHint=true already tells the agent this is a safe read, and an output schema exists, so return values need not be explained. The description adds the useful behavioral detail that results come as named 12-hour periods by default or hourly breakdowns, but says nothing about pagination or data freshness beyond what the cursor parameter already documents.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences with the core action front-loaded and the output-mode distinction second. No filler, though the space given to return format is partly redundant given the output schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With readOnlyHint, a full output schema, and 100% parameter coverage, the definition is close to complete for a forecast fetch. The notable gap is the absence of any routing between this point forecast and the sibling nws_get_zone_forecast, which an agent must otherwise infer.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already fully documents latitude, longitude, hourly, and cursor, including ranges, defaults, and the continuation token's behavior. The description restates the hourly-vs-12-hour mode but adds no syntax or meaning beyond the schema, making the baseline 3 appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Get the weather forecast') plus scope ('for a US location'), and clarifies the two output modes. It does not distinguish itself from the close sibling nws_get_zone_forecast, leaving the point-forecast-vs-zone-forecast choice unexplained.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives no when-to-use or when-not guidance and never names the obvious alternative, nws_get_zone_forecast, or when lat/lon point forecasts are preferable. Only implicit cues ('US location', the default/hourly switch) hint at appropriate use.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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Nws Get Forecast

Input Schema

Output Schema

Schema Changelog

TDQS

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