Tomorrow API

Weather / API Key Intermediate HTTPS
Varies by plan (check documentation)

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

temperature
weather conditions
humidity
wind speed
forecast data

Example Response

JSON 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

400 Bad Request Missing required location or apikey parameter
Both location and apikey are mandatory query parameters for every request
429 Too Many Requests Free tier rate limit of 25 requests per hour exceeded
Cache weather data and spread requests out; consider upgrading for higher-volume apps
Field not available in response Requested a data field not included in your subscription plan
Check the Tomorrow.io docs for which fields are available per plan; start with core fields like temperature and precipitationProbability

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 20/20
🔒 Security 15/15
🛠 Developer XP 12/20
✓ Reliability 10/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Weather
Difficulty Intermediate
Verified: 2026-04-07

Alternatives to Tomorrow

Technical alternatives for different use cases.

Micro-weather and hyperlocal forecasting capabilities

Better For

General consumer weather app use cases

Trade-off

Hyperlocal weather for logistics and agriculture

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