Overview
Tomorrow.io (formerly ClimaCell) is an advanced weather API powered by proprietary sensing technology that combines satellite, radar, and on-the-ground sensors for hyper-accurate forecasts. It delivers minute-by-minute, hourly, and daily forecasts with an extensive range of weather fields including precipitation probability, visibility, and pollen levels. Beginners can start with the free tier to build precise weather apps that go beyond basic temperature and wind data.
Beginner Tip
Register at tomorrow.io to get a free API key. The realtime endpoint is the easiest starting point — just supply a location as "lat,lon" or a city name and your API key as a query parameter.
Available Data
Example Response
{
"location": "Tokyo",
"temperature": {
"current": 22,
"feels_like": 24,
"min": 18,
"max": 26
},
"condition": "Partly Cloudy",
"humidity": 65,
"wind": {
"speed": 12,
"direction": "NE"
},
"forecast": [
{
"date": "2025-01-16",
"high": 25,
"low": 17,
"condition": "Sunny"
}
]
} Field Reference
data.values.temperature Current air temperature in Celsius (or Fahrenheit if units=imperial) data.values.humidity Relative humidity as a percentage data.values.precipitationProbability Probability of precipitation as a percentage (0-100) data.values.windSpeed Wind speed in meters per second data.values.visibility Horizontal visibility in kilometers data.time ISO 8601 timestamp for when the data point is valid Implementation Example
const url = "https://docs.tomorrow.io/";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
headers: {
"X-API-Key": "YOUR_API_KEY"
}
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); What Can You Build?
Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.
Common Errors & Troubleshooting
Matrix Score Breakdown
Partially tested on Apr 5, 2026
Technical Specifications
Alternatives to Tomorrow
Technical alternatives for different use cases.
Micro-weather and hyperlocal forecasting capabilities
General consumer weather app use cases
Hyperlocal weather for logistics and agriculture
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