API Documentation

Programmatic access to near real-time METAR-sourced weather station data, predictions, and historical observations.

All values use metric units — temperatures in °C, wind in km/h, pressure in hPa, precipitation in mm. Timestamps are station-local (each response includes a timezone field); dates are YYYY-MM-DD. Nullable fields return null when data is unavailable.

Authentication

All API endpoints require a Pro plan and a valid API key. Generate keys from your Account page.

Include your key in the Authorization header:

curl -H "Authorization: Bearer dh_live_xxxxx" \
  https://dailyhigh.app/api/v1/stations

Keys are prefixed with dh_live_. Store them securely — you can create up to 5 active keys and revoke them at any time.

Rate Limits

Rate limits are applied per API key using a sliding 60-second window. Every response includes these headers:

Header	Description
X-RateLimit-Limit	Maximum requests allowed per window
X-RateLimit-Remaining	Requests remaining in the current window
X-RateLimit-Reset	Seconds until the window resets
Retry-After	Only on 429 — seconds to wait before retrying

Endpoint	Limit	Cache TTL
/api/v1/weather/:icao	120 req/min	~15 s
/api/v1/stations	30 req/min	1 h (static metadata)
/api/v1/prediction/:icao	60 req/min	~2 min (30 min stale)
/api/v1/history/:icao/:date	60 req/min	15 s (today) · 1 h (past)

Endpoints

GET/api/v1/stations30 req/min

Returns metadata for every tracked METAR-reporting station, identified by 4-letter ICAO airport codes. Codes are uppercase in responses but accepted case-insensitively in requests. Use this endpoint to discover all available stations before calling other endpoints.

Example Request

curl -H "Authorization: Bearer dh_live_xxxxx" \
  https://dailyhigh.app/api/v1/stations

Response

{
  "ok": true,
  "data": [
    {
      "icao": "EGLC",
      "name": "London",
      "country": "gb",
      "timezone": "Europe/London",
      "region": "maritime",
      "latitude": 51.505,
      "longitude": 0.055,
      "elevation": 5.8,
      "peakHour": 15
    }
  ]
}

Response Fields — data

Field	Type	Description
icao	`string`	ICAO airport code identifying the weather station (e.g. "EGLC").
name	`string`	Human-readable station/city name (e.g. "London").
country	`string`	Two-letter ISO 3166-1 country code, lowercase (e.g. "gb").
timezone	`string`	IANA timezone of the station (e.g. "Europe/London"). Use this to interpret any local timestamps.
region	`string`	Climate region classification. One of: "desert", "coastal", "continental", "maritime", "tropical".
latitude	`number`	Station latitude in decimal degrees (WGS-84). Positive = north.
longitude	`number`	Station longitude in decimal degrees (WGS-84). Positive = east.
elevation	`number \| null`	Station elevation above mean sea level in metres.
peakHour	`number`	Typical hour (0–23, local time) when the daily maximum temperature occurs. Seasonally adjusted ±0.5 h.

GET/api/v1/weather/:icao120 req/min

Comprehensive current weather for a single station, sourced from METAR observations. Includes full atmospheric observation, today's observed extremes, sun times, station metadata, and today's forecast. Data is cached for ~15 seconds — polling faster returns the same snapshot.

Path / Query Parameters

Field	Type	Description
:icao	`string`	ICAO airport code, case-insensitive (e.g. "EGLC" or "eglc").

Example Request

curl -H "Authorization: Bearer dh_live_xxxxx" \
  https://dailyhigh.app/api/v1/weather/EGLC

Response

{
  "ok": true,
  "data": {
    "icao": "EGLC",
    "name": "London",
    "country": "gb",
    "timezone": "Europe/London",
    "region": "maritime",
    "latitude": 51.505,
    "longitude": 0.055,
    "elevation": 5.8,
    "peakHour": 15,
    "temperature": 8.2,
    "feelsLike": 6.1,
    "dewPoint": 4.3,
    "humidity": 72,
    "windSpeed": 15,
    "windGust": 24,
    "windDirection": "SW",
    "windDirectionDeg": 220,
    "pressure": 1018.5,
    "pressureTrend": "Falling",
    "visibility": 14.0,
    "uvIndex": 2,
    "uvDescription": "Low",
    "cloudCover": 50,
    "cloudCeiling": 1200,
    "precip1Hour": 0,
    "precip24Hour": 2.4,
    "conditions": "Partly Cloudy",
    "icon": "⛅",
    "dayOrNight": "D",
    "observationTime": "2026-02-10T14:20:00+00:00",
    "todayMax": 9.1,
    "todayMin": 4.3,
    "tempChange24h": 1.5,
    "sunrise": "2026-02-10T07:24:00",
    "sunset": "2026-02-10T17:05:00",
    "forecast": { "maxTemp": 10, "minTemp": 3 }
  }
}

Response Fields — data

Field	Type	Description
icao	`string`	ICAO station code.
name	`string`	Station/city name.
country	`string`	ISO 3166-1 country code (lowercase).
timezone	`string`	IANA timezone. All "local" fields use this timezone.
region	`string`	Climate region: "desert" \| "coastal" \| "continental" \| "maritime" \| "tropical".
latitude	`number`	Station latitude (decimal degrees, WGS-84).
longitude	`number`	Station longitude (decimal degrees, WGS-84).
elevation	`number \| null`	Elevation above MSL in metres.
peakHour	`number`	Typical hour of daily max temperature (local time, 0–23).
temperature	`number \| null`	Current observed air temperature in °C.
feelsLike	`number \| null`	"Feels like" temperature in °C. Combines wind chill and heat index.
dewPoint	`number \| null`	Dew point temperature in °C.
humidity	`number \| null`	Relative humidity percentage (0–100).
windSpeed	`number \| null`	Sustained wind speed in km/h.
windGust	`number \| null`	Wind gust speed in km/h. Null if no gust reported.
windDirection	`string \| null`	Cardinal wind direction (e.g. "NW", "SSE").
windDirectionDeg	`number \| null`	Wind direction in degrees (0–360, 0 = north, clockwise).
pressure	`number \| null`	Mean sea-level pressure (QNH) in hPa (mbar). Comparable across stations regardless of elevation.
pressureTrend	`string \| null`	Pressure trend: "Rising", "Falling", or "Steady".
visibility	`number \| null`	Horizontal visibility in km.
uvIndex	`number \| null`	UV index (0–11+). Null during nighttime hours — check dayOrNight to distinguish.
uvDescription	`string \| null`	UV severity label (e.g. "Low", "Moderate", "High", "Very High", "Extreme").
cloudCover	`number \| null`	Cloud cover percentage (0–100).
cloudCeiling	`number \| null`	Cloud ceiling height in metres. Null if sky is clear.
precip1Hour	`number \| null`	Precipitation in the last 1 hour in mm.
precip24Hour	`number \| null`	Precipitation in the last 24 hours in mm.
conditions	`string \| null`	Human-readable weather condition (e.g. "Partly Cloudy", "Light Rain").
icon	`string`	Weather emoji derived from current conditions (e.g. "☀️", "🌧️", "☁️", "❄️"). Day/night aware: clear skies return "🌙" after dark.
dayOrNight	`string \| null`	"D" for day, "N" for night, based on local sunrise/sunset.
observationTime	`string`	ISO 8601 timestamp with UTC offset (e.g. "2026-02-10T14:20:00+00:00"). Use the timezone field for local conversion.
todayMax	`number \| null`	Highest observed temperature today in °C. Resets at local midnight; may be null early morning before the first observation.
todayMin	`number \| null`	Lowest observed temperature today in °C. Resets at local midnight; may be null early morning before the first observation.
tempChange24h	`number \| null`	Temperature change vs. 24 hours ago in °C. Positive = warmer.
sunrise	`string \| null`	Today's sunrise in station-local time (no offset suffix). Use the timezone field to interpret.
sunset	`string \| null`	Today's sunset in station-local time (no offset suffix). Use the timezone field to interpret.
forecast	`object \| null`	Today's forecast. Null if unavailable.

Nested — forecast

Field	Type	Description
forecast.maxTemp	`number`	Forecasted daily maximum temperature in °C.
forecast.minTemp	`number`	Forecasted daily minimum temperature in °C.

GET/api/v1/prediction/:icao60 req/min

Today's daily-high temperature prediction with confidence score and reasoning. Re-computed every ~2 minutes. Returns 202 if not yet available this cycle (retry after 30 s). A top-level 'stale: true' flag means data is from a previous cycle (up to 30 min old) while a fresh prediction is being computed.

Path / Query Parameters

Field	Type	Description
:icao	`string`	ICAO airport code, case-insensitive.

Example Request

curl -H "Authorization: Bearer dh_live_xxxxx" \
  https://dailyhigh.app/api/v1/prediction/EGLC

Response

{
  "ok": true,
  "data": {
    "currentTemp": 8.2,
    "observedMax": 9.1,
    "predictedMax": 10.3,
    "forecastMax": 10.0,
    "modelMax": 10.1,
    "climoMax": 9.5,
    "confidence": 7,
    "predictionReason": "Warming trend",
    "reasoning": [
      "About 4h until peak warming",
      "Temperatures still climbing",
      "Observed temps tracking close to prediction"
    ],
    "isPastPeak": false,
    "hoursUntilPeak": 3.5,
    "slope": 1.2,
    "slopeWindow": "90 min"
  }
}

Response Fields — data

Field	Type	Description
currentTemp	`number`	Current temperature at the station in °C.
observedMax	`number`	Highest temperature observed so far today in °C.
predictedMax	`number`	DailyHigh's prediction for today's maximum temperature in °C. Updated every ~2 minutes using the latest observations and near real-time trajectory.
forecastMax	`number`	Third-party forecast max for today in °C.
modelMax	`number \| null`	Numerical weather model max in °C, bias-corrected for the station.
climoMax	`number \| null`	Climatological average daily high for this date and station in °C.
confidence	`number`	Confidence score from 1 (low) to 10 (high). Rises through the day as more observations arrive and models converge.
predictionReason	`string`	Short one-line summary of the prediction logic (e.g. "Warming trend", "Near peak").
reasoning	`string[]`	Array of human-readable reasoning lines with emoji prefixes, explaining the prediction factors.
isPastPeak	`boolean`	Whether the station has likely passed its daily temperature peak. Based on solar noon and the temperature trajectory.
hoursUntilPeak	`number`	Estimated hours remaining until the daily temperature peak. 0 if past peak. Uses station-local solar time.
slope	`number \| null`	Temperature rate of change in °C/hour over the last 90 minutes. Positive = warming, negative = cooling.
slopeWindow	`string \| null`	Description of the window used for slope calculation (e.g. "90 min").

GET/api/v1/history/:icao/:date60 req/min

Hourly weather observations for a station on a specific date. Returns the full 24-hour profile with max/min summary and sun times.

Path / Query Parameters

Field	Type	Description
:icao	`string`	ICAO airport code, case-insensitive.
:date	`string`	Calendar date in YYYY-MM-DD format, in the station's local timezone. Use today's date for live intra-day data.

Example Request

curl -H "Authorization: Bearer dh_live_xxxxx" \
  https://dailyhigh.app/api/v1/history/EGLC/2026-02-09

Response

{
  "ok": true,
  "data": {
    "date": "2026-02-09",
    "icao": "EGLC",
    "name": "London City",
    "timezone": "Europe/London",
    "maxTemp": 9.8,
    "minTemp": 3.2,
    "sunrise": "2026-02-09T07:24:00",
    "sunset": "2026-02-09T17:05:00",
    "forecast": { "maxTemp": 10, "minTemp": 3 },
    "hourly": [
      {
        "time": "2026-02-09T00:00:00",
        "temperature": 4.1,
        "conditions": "Clear",
        "humidity": 85,
        "windSpeed": 8
      }
    ]
  }
}

Response Fields — data

Field	Type	Description
date	`string`	The requested date in YYYY-MM-DD format (station-local calendar date).
icao	`string`	ICAO station code.
name	`string`	Station name.
timezone	`string`	IANA timezone of the station. All times in the hourly array are in this timezone.
maxTemp	`number \| null`	Observed daily maximum temperature in °C for the requested date.
minTemp	`number \| null`	Observed daily minimum temperature in °C for the requested date.
sunrise	`string \| null`	Sunrise time as an ISO 8601 string in station-local time.
sunset	`string \| null`	Sunset time as an ISO 8601 string in station-local time.
forecast	`object`	The forecast that was issued for this date.
hourly	`object[]`	Array of hourly observations ordered chronologically.

Nested — forecast

Field	Type	Description
forecast.maxTemp	`number`	Forecasted daily maximum temperature in °C.
forecast.minTemp	`number`	Forecasted daily minimum temperature in °C.

Nested — hourly[]

Field	Type	Description
hourly[].time	`string`	ISO 8601 timestamp in station-local time, without offset (e.g. "2026-02-09T14:00:00"). Aligned to whole hours.
hourly[].temperature	`number \| null`	Observed temperature at this hour in °C.
hourly[].conditions	`string \| null`	Weather condition string (e.g. "Clear", "Overcast").
hourly[].humidity	`number \| null`	Relative humidity percentage (0–100).
hourly[].windSpeed	`number \| null`	Wind speed in km/h.

💡 For today's date, the hourly array grows throughout the day and is cached for ~15 seconds.

💡 For past dates, the full 24-hour array is returned and cached for 1 hour.

💡 All timestamps in the hourly array are in the station's local timezone without an offset suffix — use the top-level timezone field to interpret them.

💡 sunrise and sunset are also in station-local time.

Error Responses

Error responses use the shape { "error": "Human-readable message" }. The HTTP status code indicates the error category:

Status	Meaning	When
202	Accepted	Prediction not yet cached — retry in 30 s (prediction endpoint only)
400	Bad Request	Invalid date format or malformed parameters
401	Unauthorized	Missing / invalid API key, or account is not on the Pro plan
404	Not Found	ICAO code does not match a tracked station
429	Too Many Requests	Rate limit exceeded — check `Retry-After` header
500	Server Error	Upstream data source failure — safe to retry