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Overview

The DeltaDaemon API provides programmatic access to historical NWS forecast accuracy data for US weather stations. Quantify forecast bias, reliability, and error distributions by location, lead time, date range, and weather regime. Station metadata and the /public/* mirrors need no key; data, accuracy, and MCP endpoints require Authorization: Bearer <API key>. A dd_live_ key works everywhere; a dd_mcp_ key (from the MCP page) works only on /mcp/v1. Rate limits apply per plan (Free 10/min · 100/day, Pro 60/min · 10,000/day, Enterprise 300/min · 100,000/day) and are shared between REST and MCP calls. 401 if unauthenticated, 402 if the plan is past_due or cancelled, 403 for a key scope mismatch, 429 when rate-limited.

← How to Work with Delta Daemon

Public Endpoints →

cURL

# Base URL
https://api.deltadaemon.com/api/v1

# API Key (get one at https://deltadaemon.com/signin)
export API_KEY="dd_live_..."

# Data Sources
# - Forecasts: NWS gridpoint hourly forecasts via api.weather.gov (collected every 5 min)
# - Observations: NWS ASOS/AWOS automated station observations (collected every 5 min)
# - Daily maxima/minima: midnight-to-midnight station-local time (NWS CLI methodology)

# Temperature Convention
# - All temperatures in Fahrenheit
# - Daily max = highest observed temp during the station's local calendar day
# - Accuracy endpoints: optional metric=high (default) or metric=low (forecast_low vs daily min)

# Error Convention
# - error = forecast - observed
# - Positive error = forecast too warm (over-prediction)
# - Negative error = forecast too cool (under-prediction)
# - Stats are null (never 0) when there are no verified pairs

# Station Parameters
# - station_id: ICAO id (KLAX). city: name or alias, resolved via /stations/metadata
# - Some endpoints require one of them (400 if neither is given)

# Date Parameters
# - days: rolling window (today minus N days; default 90, max 365)
# - date_from / date_to: explicit window, station-local days (overrides days)
# - forecast_for_date: which day the forecast applies to

cURL

# Base URL
https://api.deltadaemon.com/api/v1

# API Key (get one at https://deltadaemon.com/signin)
export API_KEY="dd_live_..."

# Data Sources
# - Forecasts: NWS gridpoint hourly forecasts via api.weather.gov (collected every 5 min)
# - Observations: NWS ASOS/AWOS automated station observations (collected every 5 min)
# - Daily maxima/minima: midnight-to-midnight station-local time (NWS CLI methodology)

# Temperature Convention
# - All temperatures in Fahrenheit
# - Daily max = highest observed temp during the station's local calendar day
# - Accuracy endpoints: optional metric=high (default) or metric=low (forecast_low vs daily min)

# Error Convention
# - error = forecast - observed
# - Positive error = forecast too warm (over-prediction)
# - Negative error = forecast too cool (under-prediction)
# - Stats are null (never 0) when there are no verified pairs

# Station Parameters
# - station_id: ICAO id (KLAX). city: name or alias, resolved via /stations/metadata
# - Some endpoints require one of them (400 if neither is given)

# Date Parameters
# - days: rolling window (today minus N days; default 90, max 365)
# - date_from / date_to: explicit window, station-local days (overrides days)
# - forecast_for_date: which day the forecast applies to