nws-weather-mcp-server

Nws Get Zone Forecast

nws_get_zone_forecast

Read-only

Get the text forecast for a public NWS forecast zone. Returns named forecast periods (e.g., "Today", "Tonight", "Monday") with detailed narrative text — the human-readable, zone-level forecast written by local forecasters. Completes the alert-to-forecast chain: nws_search_alerts returns each affected zone in "affectedZones" as a code plus a type, and nws_find_stations returns codes in the "forecastZone" column. Only affectedZones entries with type "forecast" work here; entries typed "county" or "fire" have no text forecast upstream and will not resolve, and neither do marine forecast zones (e.g., "PZZ251", "GMZ056"). Zone codes follow the pattern XXZ### (e.g., "WAZ315" for Western Washington lowlands).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`zone_id`	Yes	NWS public forecast zone code (e.g., "WAZ315" for the Western Washington lowlands including Seattle). Returned as "forecastZone" by nws_get_forecast and nws_find_stations, or as the "code" of an "affectedZones" entry with type "forecast" in nws_search_alerts. Format: two-letter state + "Z" + three-digit number.

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`zoneId`	No	Zone ID, uppercased (e.g., "WAZ315" for input "waz315").
`periods`	No	Forecast periods in chronological order, typically covering 7 days.
`updated`	No	When the zone forecast was last updated (ISO 8601 with timezone offset).
`periodCount`	No	Number of forecast periods returned.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 30, 2026

changedOutput schema / properties / zoneId / description

Previous value: -"Zone ID as provided (e.g., \"WAZ315\")."New value: +"Zone ID, uppercased (e.g., \"WAZ315\" for input \"waz315\")."

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: `zone_not_found`: Zone code is not a valid public forecast zone or has no forecast available. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `zone_not_found`: Zone code is not a valid public forecast zone. `zone_forecast_unavailable`: Zone is a valid public forecast zone, but NWS has no text forecast for it. `marine_forecast_unsupported`: Zone is a marine forecast zone, for which NWS publishes no text forecast. Other values are possible when a failure originates below the handler."

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

Previous value: -[
-  "zone_not_found"
-]New value: +[
+  "zone_not_found",
+  "zone_forecast_unavailable",
+  "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: `zone_not_found`: Zone code is not a valid public forecast zone or has no forecast available Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `zone_not_found`: Zone code is not a valid public forecast zone or has no forecast available. Other values are possible when a failure originates below the handler."

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": [
+      "zoneId",
+      "updated",
+      "periods",
+      "periodCount"
+    ]
+  },
+  {
+    "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: `zone_not_found`: Zone code is not a valid public forecast zone or has no forecast available Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "zone_not_found"
+          ],
+          "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: -[
-  "zoneId",
-  "updated",
-  "periods",
-  "periodCount"
-]

Changed1 schema field changedAug 13, 2026

changedInput schema / properties / zone_id / description

Previous value: -"NWS public forecast zone code (e.g., \"WAZ315\" for the Western Washington lowlands including Seattle). Returned as \"forecastZone\" by nws_get_forecast and nws_find_stations, or in \"affectedZones\" by nws_search_alerts. Format: two-letter state + \"Z\" + three-digit number."New value: +"NWS public forecast zone code (e.g., \"WAZ315\" for the Western Washington lowlands including Seattle). Returned as \"forecastZone\" by nws_get_forecast and nws_find_stations, or as the \"code\" of an \"affectedZones\" entry with type \"forecast\" in nws_search_alerts. Format: two-letter state + \"Z\" + three-digit number."

AddedMay 30, 2026

TDQS

A4.6/5.0

Behavior4/5

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

With readOnlyHint already declaring the safety profile, the description adds meaningful behavioral context: the return is narrative, period-named text, and it discloses which zone inputs silently fail to resolve. It does not cover rate limits or exact error behavior, but the failure-mode disclosure is substantive.

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?

Purpose and output shape are front-loaded, followed by chaining guidance and exclusions. It is dense but every sentence carries information; slightly long, though no sentence is wasted.

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

Completeness5/5

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

For a single-parameter read tool with an output schema and readOnly annotation, the description supplies everything an agent needs: what it returns, how to obtain a valid zone_id, and which code families are unsupported. Nothing material is missing.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds real value: the XXZ### pattern rationale, a concrete example (WAZ315), the sources of valid codes, and the critical distinction that only "forecast"-typed affectedZones entries qualify.

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

Purpose5/5

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

States a specific verb+resource (get the text forecast for a public NWS forecast zone) and describes the output shape (named periods like "Today"/"Tonight" with narrative text). It clearly distinguishes itself from nws_get_forecast and nws_search_alerts by scope and by the alert-to-forecast chain it completes.

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

Usage Guidelines5/5

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

Explicitly names the sibling tools that produce valid inputs (nws_search_alerts affectedZones, nws_find_stations forecastZone) and states the exclusive condition: only entries typed "forecast" work. It also gives clear exclusions ("county"/"fire" types and marine zones like PZZ251/GMZ056 will not resolve).

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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