Make your first API call

You will ask the WxAlerts REST API which weather alerts are in effect at one point, then for the current weather at the same point. You need no account and no key. You need curl, or Python, or Node 18 or newer.

Browsers block calls from other websites (CORS allows only wxalerts.org), so run this from a script or a server, not from a web page.

1. Get the active alerts at a point

The point is South Lake Tahoe, California: latitude 38.94, longitude -119.98. /alerts/at takes those two parameters and nothing else.

curl "https://api.wxalerts.org/alerts/at?lat=38.94&lon=-119.98"

import json
import requests

r = requests.get(
    "https://api.wxalerts.org/alerts/at",
    params={"lat": 38.94, "lon": -119.98},
    timeout=10,
)
r.raise_for_status()
print(json.dumps(r.json(), indent=2))

const params = new URLSearchParams({ lat: "38.94", lon: "-119.98" });
const res = await fetch(`https://api.wxalerts.org/alerts/at?${params}`);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
console.log(JSON.stringify(await res.json(), null, 2));

The Python sample uses requests, so install it first with pip install requests. Save the JavaScript as first-call.mjs and run it with node first-call.mjs.

You get a JSON list with one object per alert. This is the first object, with the long text fields cut short:

[
  {
    "id": 29872029,
    "vtec_key": "KREV.WS.W.0004.2026",
    "event": "Winter Storm Warning",
    "office": "KREV",
    "phenomena": "WS",
    "significance": "W",
    "etn": 4,
    "status": "active",
    "severity": "Severe",
    "urgency": "Expected",
    "certainty": "Likely",
    "issued_at": "2026-11-12T08:33:00Z",
    "onset": "2026-11-13T18:00:00Z",
    "expires": "2026-11-13T08:45:00Z",
    "ends": "2026-11-14T18:00:00Z",
    "headline": "Winter Storm Warning issued November 12 at 12:33AM PST until November 14 at 10:00AM PST by NWS Reno NV",
    "description": "* WHAT...Heavy wet snow. Snow accumulations near 12 inches above 7000 feet...",
    "geom_source": "ugc",
    "short_id": "FfPsk4OT"
  }
]

If you get [], nothing is in effect at that point right now. That is a normal answer. Change lat and lon to a place with weather on it and run it again.

2. Read the response

Four fields tell you most of what you need:

• event is the NWS name for the hazard, here Winter Storm Warning.
• significance is W for a warning, A for a watch, Y for an advisory and S for a statement. Sort and color by this, not by severity.
• ends is when the hazard actually ends. expires is only the time an update is due, so it can be earlier than ends, as it is here.
• headline and description are the product text, unedited.

3. Get the current weather at the same point

/weather takes the same two parameters. The current object is what the nearest stations measured. The sample below prints a few of its fields.

curl "https://api.wxalerts.org/weather?lat=38.94&lon=-119.98"

import requests

r = requests.get(
    "https://api.wxalerts.org/weather",
    params={"lat": 38.94, "lon": -119.98},
    timeout=10,
)
r.raise_for_status()
current = r.json()["current"]
print(current["sky"], current["temperature"], "F, wind",
      current["wind_speed"], "mph from", current["wind_direction_cardinal"])

const params = new URLSearchParams({ lat: "38.94", lon: "-119.98" });
const res = await fetch(`https://api.wxalerts.org/weather?${params}`);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const { current } = await res.json();
console.log(current.sky, current.temperature, "F, wind",
  current.wind_speed, "mph from", current.wind_direction_cardinal);

The curl command prints the whole response. The Python and JavaScript samples print one line:

Clear 25.0 F, wind 0.0 mph from N

JavaScript prints the same numbers without the trailing .0.

You have now made a public REST call, read an alert and read a measurement. Next, subscribe to live alerts over MQTT so you never have to poll for them.