diff --git a/AGRARIAN_DEVELOPMENT_ROADMAP.md b/AGRARIAN_DEVELOPMENT_ROADMAP.md
index 8b2a52d..28d02e2 100644
--- a/AGRARIAN_DEVELOPMENT_ROADMAP.md
+++ b/AGRARIAN_DEVELOPMENT_ROADMAP.md
@@ -426,7 +426,7 @@ Target deliverable: A small group can join a server, spawn into one biome, gathe
 - [x] Add weather transition rules.
 - [x] Add weather replication.
 - [x] Add real-world weather provider adapter for Ground Zero by latitude/longitude. Added a tile-driven Open-Meteo adapter subsystem that can request weather for any active tile by center latitude/longitude, map provider weather codes into Agrarian weather states, apply current temperature and daily low/high to `AAgrarianGameState`, and generate a source-backed tile weather manifest so future real tiles become weather-eligible automatically.
-- [ ] Use Open-Meteo as the first global MVP weather source.
+- [x] Use Open-Meteo as the first global MVP weather source. Added `Data/Weather/open_meteo_mvp_source.json` as the provider contract, documented the global tile lookup rule, and added `Scripts/verify_open_meteo_mvp_source.py` to validate the static contract plus live Open-Meteo responses for every source-backed tile in the generated weather manifest.
 - [ ] Add NOAA/NWS fallback or enrichment for US tiles where useful.
 - [ ] Cache real-weather snapshots server-side so clients never call public weather APIs directly.
 - [ ] Map real weather inputs into Agrarian weather states: temperature, precipitation, wind, cloud cover, humidity, pressure, visibility, and weather code.
diff --git a/Data/Weather/open_meteo_mvp_source.json b/Data/Weather/open_meteo_mvp_source.json
new file mode 100644
index 0000000..bc0c685
--- /dev/null
+++ b/Data/Weather/open_meteo_mvp_source.json
@@ -0,0 +1,37 @@
+{
+  "schema_version": 1,
+  "provider_id": "open-meteo",
+  "provider_name": "Open-Meteo Forecast API",
+  "provider_docs_url": "https://open-meteo.com/en/docs",
+  "forecast_endpoint": "https://api.open-meteo.com/v1/forecast",
+  "api_key_required": false,
+  "tile_lookup_rule": "Use each source-backed tile center latitude/longitude from Data/Tiles/tile_weather_manifest.json.",
+  "request_parameters": {
+    "current": [
+      "temperature_2m",
+      "relative_humidity_2m",
+      "precipitation",
+      "rain",
+      "showers",
+      "snowfall",
+      "weather_code",
+      "cloud_cover",
+      "pressure_msl",
+      "wind_speed_10m"
+    ],
+    "daily": [
+      "temperature_2m_max",
+      "temperature_2m_min",
+      "weather_code",
+      "precipitation_sum",
+      "wind_speed_10m_max"
+    ],
+    "forecast_days": 1,
+    "timezone": "auto"
+  },
+  "agrarian_mapping": {
+    "temperature": "current.temperature_2m feeds RegionalObservedTemperatureC; daily min/max feed RegionalDailyLowTemperatureC and RegionalDailyHighTemperatureC.",
+    "weather_state": "weather_code, precipitation, and wind speed map into Clear, Rain, ColdWind, or Storm.",
+    "source_tracking": "provider id and provider current timestamp are stored in the game-state weather source string until full persistence metadata is implemented."
+  }
+}
diff --git a/Docs/TechnicalDesignDocument.md b/Docs/TechnicalDesignDocument.md
index 6f239cf..45ec672 100644
--- a/Docs/TechnicalDesignDocument.md
+++ b/Docs/TechnicalDesignDocument.md
@@ -157,6 +157,14 @@ source-backed, generated, validated, packaged, or published tile with center
 coordinates, while placeholder/unknown tiles are skipped. Future source-backed
 tiles therefore become weather-eligible when their registry entries are added.
 
+Open-Meteo is the first global MVP weather source. The provider contract is
+stored in `Data/Weather/open_meteo_mvp_source.json`, including the forecast
+endpoint, requested current/daily variables, tile lookup rule, and Agrarian
+mapping notes. `Scripts/verify_open_meteo_mvp_source.py` validates the static
+contract and can perform a live Open-Meteo request for every source-backed tile
+in `Data/Tiles/tile_weather_manifest.json`. This keeps the provider global for
+all future real tiles instead of adding one-off Ground Zero weather code.
+
 ## Terrain And Tile Delivery
 
 ### MVP Tile
diff --git a/Scripts/verify_open_meteo_mvp_source.py b/Scripts/verify_open_meteo_mvp_source.py
new file mode 100644
index 0000000..44a1f2d
--- /dev/null
+++ b/Scripts/verify_open_meteo_mvp_source.py
@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+"""Verify Open-Meteo is the global MVP weather source for source-backed tiles."""
+
+from __future__ import annotations
+
+import json
+import os
+import urllib.parse
+import urllib.request
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+PROVIDER_CONTRACT = ROOT / "Data" / "Weather" / "open_meteo_mvp_source.json"
+TILE_MANIFEST = ROOT / "Data" / "Tiles" / "tile_weather_manifest.json"
+WEATHER_SUBSYSTEM_CPP = ROOT / "Source" / "AgrarianGame" / "AgrarianWeatherProviderSubsystem.cpp"
+WEATHER_SUBSYSTEM_H = ROOT / "Source" / "AgrarianGame" / "AgrarianWeatherProviderSubsystem.h"
+ROADMAP = ROOT / "AGRARIAN_DEVELOPMENT_ROADMAP.md"
+TDD = ROOT / "Docs" / "TechnicalDesignDocument.md"
+
+
+EXPECTED_SNIPPETS = {
+    WEATHER_SUBSYSTEM_H: [
+        "OpenMeteoForecastEndpoint",
+        "https://api.open-meteo.com/v1/forecast",
+        "RequestWeatherForTile",
+    ],
+    WEATHER_SUBSYSTEM_CPP: [
+        "current=temperature_2m,relative_humidity_2m,precipitation",
+        "daily=temperature_2m_max,temperature_2m_min,weather_code,precipitation_sum,wind_speed_10m_max",
+        "OutSnapshot.Provider = TEXT(\"open-meteo\");",
+    ],
+    ROADMAP: [
+        "[x] Use Open-Meteo as the first global MVP weather source.",
+    ],
+    TDD: [
+        "Open-Meteo is the first global MVP weather source",
+        "Data/Weather/open_meteo_mvp_source.json",
+    ],
+}
+
+
+def assert_static_contract() -> tuple[dict, dict]:
+    missing = []
+    for path, snippets in EXPECTED_SNIPPETS.items():
+        text = path.read_text(encoding="utf-8")
+        for snippet in snippets:
+            if snippet not in text:
+                missing.append(f"{path.relative_to(ROOT)}: {snippet}")
+    if missing:
+        raise RuntimeError("Open-Meteo MVP source verification failed: " + "; ".join(missing))
+
+    provider = json.loads(PROVIDER_CONTRACT.read_text(encoding="utf-8"))
+    manifest = json.loads(TILE_MANIFEST.read_text(encoding="utf-8"))
+    if provider.get("provider_id") != "open-meteo":
+        raise RuntimeError("Provider contract does not identify Open-Meteo")
+    if provider.get("api_key_required") is not False:
+        raise RuntimeError("Open-Meteo MVP source should not require an API key")
+    if not manifest.get("tiles"):
+        raise RuntimeError("Tile weather manifest has no source-backed weather tiles")
+    for tile in manifest["tiles"]:
+        if tile.get("provider") != "open-meteo":
+            raise RuntimeError(f"Unexpected tile weather provider for {tile.get('tile_id')}: {tile.get('provider')}")
+    return provider, manifest
+
+
+def build_open_meteo_url(provider: dict, tile: dict) -> str:
+    params = provider["request_parameters"]
+    query = {
+        "latitude": f"{float(tile['center_latitude']):.6f}",
+        "longitude": f"{float(tile['center_longitude']):.6f}",
+        "current": ",".join(params["current"]),
+        "daily": ",".join(params["daily"]),
+        "forecast_days": str(params["forecast_days"]),
+        "timezone": params["timezone"],
+    }
+    return provider["forecast_endpoint"] + "?" + urllib.parse.urlencode(query, safe=",")
+
+
+def assert_live_open_meteo_response(provider: dict, manifest: dict) -> None:
+    if os.environ.get("AGRARIAN_SKIP_LIVE_WEATHER_CHECK") == "1":
+        print("Skipping live Open-Meteo check because AGRARIAN_SKIP_LIVE_WEATHER_CHECK=1")
+        return
+
+    for tile in manifest["tiles"]:
+        url = build_open_meteo_url(provider, tile)
+        with urllib.request.urlopen(url, timeout=20) as response:
+            payload = json.loads(response.read().decode("utf-8"))
+
+        current = payload.get("current", {})
+        daily = payload.get("daily", {})
+        required_current = {"temperature_2m", "relative_humidity_2m", "precipitation", "weather_code", "wind_speed_10m"}
+        required_daily = {"temperature_2m_max", "temperature_2m_min", "weather_code", "precipitation_sum"}
+        missing_current = sorted(required_current - set(current))
+        missing_daily = sorted(required_daily - set(daily))
+        if missing_current or missing_daily:
+            raise RuntimeError(
+                f"Open-Meteo response for {tile['tile_id']} missing current={missing_current} daily={missing_daily}"
+            )
+        if not isinstance(daily["temperature_2m_max"], list) or not daily["temperature_2m_max"]:
+            raise RuntimeError(f"Open-Meteo daily max temperature is empty for {tile['tile_id']}")
+
+
+def main() -> None:
+    provider, manifest = assert_static_contract()
+    assert_live_open_meteo_response(provider, manifest)
+    print("Open-Meteo MVP weather source verification complete.")
+
+
+if __name__ == "__main__":
+    main()