WeatherArb API — Weather Intelligence Platform

🔑

Authentication

The Free tier requires no authentication. Simply call the endpoints directly. For Pro tier (higher rate limits and advanced endpoints), include your API key in the request header.

Free Tier — No Auth Required

cURL

curl "https://api.weatherarb.com/api/v1/pulse/milan"

Pro Tier — API Key Header

cURL
Python
JavaScript

      curl -H "X-API-Key: your_key_here" \
     "https://api.weatherarb.com/api/v1/global/top?limit=100"
    

      import requests

headers = {"X-API-Key": "your_key_here"}
r = requests.get(
    "https://api.weatherarb.com/api/v1/global/top",
    headers=headers, params={"limit": 100}
)
data = r.json()
print(data["count"], "anomalies detected")
    

      const response = await fetch(
  "https://api.weatherarb.com/api/v1/global/top?limit=100",
  { headers: { "X-API-Key": "your_key_here" } }
);
const data = await response.json();
console.log(data.reports.length, "cities");
    

⚡

Pulse Endpoints

Real-time weather anomaly data for individual cities. Returns Z-Score, temperature, HDD/CDD, wind, humidity, and sector impact analysis.

GET /api/v1/pulse/{city_slug} FREE City anomaly data

Returns real-time weather anomaly data for a specific city. The city_slug is the URL-encoded city name (lowercase, hyphens). Z-Score is calculated against the 25-year NASA POWER ERA5-Land baseline for that exact location.

Path Parameters

Parameter	Type	Description
city_slugrequired	string	City name slug (e.g. `milan`, `new-york`, `sao-paulo`)

cURL
Python
JavaScript
Go

          
          curl "https://api.weatherarb.com/api/v1/pulse/milan"
        

          import requests

r = requests.get("https://api.weatherarb.com/api/v1/pulse/milan")
d = r.json()

w = d["weather"]
print(f"Milan Z-Score: {w['z_score']:+.2f}σ")
print(f"Temperature: {w['temperature_c']}°C")
print(f"Anomaly: {w['anomaly_level']}")
        

          const r = await fetch("https://api.weatherarb.com/api/v1/pulse/milan");
const { weather, signal } = await r.json();

console.log(`Z-Score: ${weather.z_score > 0 ? '+' : ''}${weather.z_score.toFixed(2)}σ`);
console.log(`Score: ${signal.score}/10`);
console.log(`Event: ${weather.anomaly_label}`);
        

          package main

import (
    "encoding/json"
    "fmt"
    "net/http"
)

func main() {
    resp, _ := http.Get("https://api.weatherarb.com/api/v1/pulse/milan")
    var data map[string]interface{}
    json.NewDecoder(resp.Body).Decode(&data)
    weather := data["weather"].(map[string]interface{})
    fmt.Printf("Z-Score: %v\n", weather["z_score"])
}
        

200 OK Response

{
  "city": "milan",
  "location": "Milan",
  "country_code": "it",
  "lat": 45.46,
  "lon": 9.19,
  "weather": {
    "z_score": +2.14,           // Standard deviations from 25yr baseline
    "temperature_c": 28.4,      // Current temperature (°C)
    "humidity_pct": 62,          // Relative humidity (%)
    "wind_kmh": 14,              // Wind speed (km/h)
    "hdd": 0.0,                  // Heating degree days
    "cdd": 3.4,                  // Cooling degree days
    "hdd_delta": -2.1,           // HDD vs historical average
    "anomaly_level": "EXTREME",  // NORMAL|UNUSUAL|EXTREME|CRITICAL
    "anomaly_label": "Heat wave",
    "event_type": "heat_wave"
  },
  "signal": {
    "score": 7.8,               // 0-10 composite risk score
    "vertical": "heat_wave",
    "agri_impact": "high",
    "energy_impact": "high",
    "logistics_impact": "moderate"
  },
  "timestamp": "2026-05-06T18:00:00Z"
}

GET /api/v1/pulse/nearby FREE Nearest city by coordinates

Find the nearest monitored city to a given latitude/longitude and return its live anomaly data. Useful for geolocation-based applications.

Parameter	Type	Description
latrequired	float	Latitude (-90 to 90)
lonrequired	float	Longitude (-180 to 180)

curl "https://api.weatherarb.com/api/v1/pulse/nearby?lat=45.46&lon=9.19"

🌍

Intelligence Endpoints

Aggregate anomaly intelligence across regions, countries, and globally. Returns ranked lists of cities with active weather anomalies.

GET /api/v1/europe/top FREE Top European anomalies

Returns the top anomalies across all monitored cities, sorted by absolute Z-Score. Default limit is 50.

Parameter	Type	Description
limitoptional	integer	Max results (default: 50, max free: 100, max pro: 500)
min_scoreoptional	float	Minimum score filter (0-10)

curl "https://api.weatherarb.com/api/v1/europe/top?limit=10&min_score=5"

GET /api/v1/global/top FREE Top global anomalies

Returns top anomalies globally across all 10,385 monitored cities. Includes heat waves, cold snaps, heavy rain events ranked by severity.

Parameter	Type	Description
limitoptional	integer	Max results (default: 50)
event_typeoptional	string	Filter: `heat_wave`, `cold_snap`, `heavy_rain`, `drought`

cURL
Python

          curl "https://api.weatherarb.com/api/v1/global/top?limit=20&event_type=heat_wave"
        

          import requests

params = {"limit": 20, "event_type": "heat_wave"}
r = requests.get("https://api.weatherarb.com/api/v1/global/top", params=params)
data = r.json()

for city in data["reports"]:
    z = city["z_score"]
    print(f"{city['location']:20} Z={z:+.2f}σ  Score={city['score']:.1f}")
        

GET /api/v1/country/{country_code} FREE Country anomalies

Returns all monitored cities and their anomaly data for a specific country (ISO 3166-1 alpha-2 code).

Parameter	Type	Description
country_coderequired	string	ISO country code: `it`, `us`, `de`, `fr`, `in`...

curl "https://api.weatherarb.com/api/v1/country/it"
curl "https://api.weatherarb.com/api/v1/country/us"
curl "https://api.weatherarb.com/api/v1/country/in"

GET /api/v1/critical FREE Critical anomalies only (|Z|≥3σ)

Returns only cities with critical anomalies (absolute Z-Score ≥ 3σ). These represent statistically extreme weather events occurring less than 0.3% of the time historically.

curl "https://api.weatherarb.com/api/v1/critical"

GET /api/v1/leaderboard FREE Anomaly leaderboard

Top anomalies ranked by composite score (0-10). Score combines Z-Score magnitude, HDD/CDD impact, wind, humidity, and duration.

curl "https://api.weatherarb.com/api/v1/leaderboard?limit=20"

📊

Analytics Endpoints

System statistics, grid stress analysis, and cache management.

GET /api/v1/stats FREE Platform statistics

Returns platform-wide statistics: total nodes, cached nodes, critical count, average Z-Score, and last update timestamp.

cURL
Response

          curl "https://api.weatherarb.com/api/v1/stats"
        

          {
  "total_nodes": 10385,
  "cached_nodes": 500,
  "critical_count": 27,
  "avg_z_score": 1.24,
  "countries": 120,
  "last_updated": "2026-05-06T18:00:00Z",
  "cache_age_seconds": 3240
}
        

GET /api/v1/grid-stress PRO Energy grid stress index

Returns energy grid stress scores per country, space weather data (Kp index, solar flare class), and risk assessments for critical infrastructure.

curl -H "X-API-Key: your_key" \
     "https://api.weatherarb.com/api/v1/grid-stress"

POST /pulse/refresh FREE Trigger cache refresh

Triggers a background refresh of all weather data from Open-Meteo. Returns immediately; data available after ~30 seconds.

curl -X POST "https://api.weatherarb.com/pulse/refresh"
# Response:
{
  "status": "refresh_started",
  "province_count": 10385,
  "message": "Data available in ~30 seconds"
}

🗂️

Data Model

Complete reference for all fields returned by the API.

Weather Object

z_score

float

Standard deviations from 25-year NASA POWER baseline. |Z|≥2 = extreme, |Z|≥3 = critical

temperature_c

float

Current air temperature in Celsius

humidity_pct

integer

Relative humidity percentage (0-100)

wind_kmh

float

Wind speed in km/h at 10m height

hdd

float

Heating Degree Days (base 18°C, EN ISO 15927)

cdd

float

Cooling Degree Days (base 18°C)

hdd_delta

float

HDD deviation vs 25-year historical average

anomaly_level

string

NORMAL · UNUSUAL · EXTREME · CRITICAL

anomaly_label

string

Human-readable event: "Heat wave", "Cold snap", "Heavy rain"

event_type

string

Machine-readable: heat_wave · cold_snap · heavy_rain · drought · normal

Signal Object

score

float 0-10

Composite risk score combining all anomaly metrics

agri_impact

string

Agricultural impact: low · moderate · high · critical

energy_impact

string

Energy grid impact level

logistics_impact

string

Transportation/logistics risk level

🧪

Live Playground

Test the API directly from your browser. No authentication required.

City Pulse — /api/v1/pulse/{city}

https://api.weatherarb.com/api/v1/pulse/milan

Top Anomalies — /api/v1/europe/top

https://api.weatherarb.com/api/v1/europe/top?limit=5

Nearest City — /api/v1/pulse/nearby

https://api.weatherarb.com/api/v1/pulse/nearby?lat=45.46&lon=9.19

⚡

Rate Limits

Rate limits are applied per IP address on the free tier and per API key on paid plans.

Free

60

requests / hour

Starter

1,000

requests / hour

Pro

10,000

requests / hour

Rate limit headers are included in every response: X-RateLimit-Remaining, X-RateLimit-Reset.

⚠️

Error Codes

All errors return JSON with error and message fields.

200

OK

Request succeeded. Data returned in response body.

404

City Not Found

The requested city slug does not exist in our database. Check spelling or try a nearby city.

429

Rate Limit Exceeded

Too many requests. Wait for the reset window or upgrade to a paid plan.

500

Server Error

Internal server error. Weather data may be refreshing. Retry after 30 seconds.

503

Cache Empty

Weather cache not yet populated. POST to /pulse/refresh and retry after 30 seconds.

💎

Pricing

Start free, scale as you grow. No credit card required for the free tier.

Free

€0/month

Perfect for personal projects and testing

60 requests / hour
All pulse endpoints
Top 100 anomalies
JSON responses
API key required
Grid stress data
Historical data
Webhooks

Get Started Free

Pro

€49/month

For businesses and production applications

10,000 requests / hour
All endpoints
Full 10,385 city database
Grid stress & space weather
Sector impact analytics
Priority support
Historical time series
Custom baselines

Start Pro Trial

Enterprise

Custom

For large-scale weather intelligence applications

Unlimited requests
Custom city additions
Historical time series
Custom baselines
Dedicated infrastructure
SLA guarantee
White-label option
Custom integrations

Contact Sales

WeatherArbIntelligence API

Authentication

Free Tier — No Auth Required

Pro Tier — API Key Header

Pulse Endpoints

Path Parameters

Intelligence Endpoints

Analytics Endpoints

Data Model

Weather Object

Signal Object

Live Playground

Rate Limits

Error Codes

Pricing

WeatherArb
Intelligence API