OpenWeatherMap API
api.openweathermap.org · Science
Current weather, forecasts, historical data, and weather maps for any location. 60+ years of weather archive, global coverage. Free tier: 1,000 calls/day.
Authentication
API Key
Free API key at openweathermap.org. Pass as ?appid= query parameter or Authorization: Bearer header.
Sample Requests
GET
Current weather by city
Get current weather for London.
https://api.openweathermap.org/data/2.5/weather?q=London&appid=YOUR_API_KEY&units=metric
Hover any highlighted part to learn what it does
curl -X GET "https://api.openweathermap.org/data/2.5/weather?q=London&appid=YOUR_API_KEY&units=metric"
import requests
params = {
"q": "London",
"appid": "YOUR_API_KEY",
"units": "metric"
}
response = requests.get(
"https://api.openweathermap.org/data/2.5/weather",
params=params,
)
print(response.json())const url = new URL('https://api.openweathermap.org/data/2.5/weather');
url.searchParams.set('q', 'London');
url.searchParams.set('appid', 'YOUR_API_KEY');
url.searchParams.set('units', 'metric');
const response = await fetch(url);
const data = await response.json();
console.log(data);package main
import (
"fmt"
"io"
"net/http"
"net/url"
)
func main() {
baseURL, _ := url.Parse("https://api.openweathermap.org/data/2.5/weather")
q := baseURL.Query()
q.Set("q", "London")
q.Set("appid", "YOUR_API_KEY")
q.Set("units", "metric")
baseURL.RawQuery = q.Encode()
targetURL := baseURL.String()
req, _ := http.NewRequest("GET", targetURL, nil)
client := &http.Client{}
resp, _ := client.Do(req)
defer resp.Body.Close()
body, _ := io.ReadAll(resp.Body)
fmt.Println(string(body))
}require "net/http"
require "json"
uri = URI("https://api.openweathermap.org/data/2.5/weather")
uri.query = URI.encode_www_form({
"q" => "London",
"appid" => "YOUR_API_KEY",
"units" => "metric"
})
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"
req = Net::HTTP::Get.new(uri)
res = http.request(req)
puts JSON.parse(res.body)<?php
$url = "https://api.openweathermap.org/data/2.5/weather?" . http_build_query([
"q" => "London",
"appid" => "YOUR_API_KEY",
"units" => "metric"
]);
$opts = ["http" => [
"method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));
GET
5-day forecast
Get 5-day/3-hour forecast for New York.
https://api.openweathermap.org/data/2.5/forecast?q=New York&cnt=10&appid=YOUR_API_KEY&units=imperial
Hover any highlighted part to learn what it does
curl -X GET "https://api.openweathermap.org/data/2.5/forecast?q=New%20York&cnt=10&appid=YOUR_API_KEY&units=imperial"
import requests
params = {
"q": "New York",
"cnt": "10",
"appid": "YOUR_API_KEY",
"units": "imperial"
}
response = requests.get(
"https://api.openweathermap.org/data/2.5/forecast",
params=params,
)
print(response.json())const url = new URL('https://api.openweathermap.org/data/2.5/forecast');
url.searchParams.set('q', 'New York');
url.searchParams.set('cnt', '10');
url.searchParams.set('appid', 'YOUR_API_KEY');
url.searchParams.set('units', 'imperial');
const response = await fetch(url);
const data = await response.json();
console.log(data);package main
import (
"fmt"
"io"
"net/http"
"net/url"
)
func main() {
baseURL, _ := url.Parse("https://api.openweathermap.org/data/2.5/forecast")
q := baseURL.Query()
q.Set("q", "New York")
q.Set("cnt", "10")
q.Set("appid", "YOUR_API_KEY")
q.Set("units", "imperial")
baseURL.RawQuery = q.Encode()
targetURL := baseURL.String()
req, _ := http.NewRequest("GET", targetURL, nil)
client := &http.Client{}
resp, _ := client.Do(req)
defer resp.Body.Close()
body, _ := io.ReadAll(resp.Body)
fmt.Println(string(body))
}require "net/http"
require "json"
uri = URI("https://api.openweathermap.org/data/2.5/forecast")
uri.query = URI.encode_www_form({
"q" => "New York",
"cnt" => "10",
"appid" => "YOUR_API_KEY",
"units" => "imperial"
})
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = uri.scheme == "https"
req = Net::HTTP::Get.new(uri)
res = http.request(req)
puts JSON.parse(res.body)<?php
$url = "https://api.openweathermap.org/data/2.5/forecast?" . http_build_query([
"q" => "New York",
"cnt" => "10",
"appid" => "YOUR_API_KEY",
"units" => "imperial"
]);
$opts = ["http" => [
"method" => "GET",
]];
$ctx = stream_context_create($opts);
$res = file_get_contents($url, false, $ctx);
print_r(json_decode($res, true));Postman Setup Guide
- Get a free API key at openweathermap.org/api
- Pass appid=YOUR_KEY as query param
- Try GET https://api.openweathermap.org/data/2.5/weather?q=Paris&appid=YOUR_KEY&units=metric
- units: metric (°C), imperial (°F), standard (Kelvin)
What can you build with OpenWeatherMap API?
OpenWeatherMap API is a Science API. Developers commonly use science APIs for:
- accessing research datasets and scientific literature
- powering academic and R&D applications
- running scientific calculations and simulations
- visualising experimental and observational data
- integrating with research and reference databases
API Key authentication. You'll receive a key after signing up. Send it with every request — in a header or query parameter. Keep it out of client-side code and never commit it to version control. OpenWeatherMap API is free to use up to a usage limit, making it a low-risk choice to experiment with.
New to APIs? Read our beginner's guide · Learn about API keys · What is REST?