Forecasts

Overview

The Forecasts domain provides APIs spanning short-range (15-minute) through seasonal time horizons, covering standard weather parameters, lifestyle indices, precipitation analytics, radar-derived products, and probabilistic forecasts. Data is sourced from The Weather Company Forecast System and delivered through structured JSON responses, Tiler (gridded raster tiles), and Featurizer (vector threshold features). Most APIs support global coverage with multi-format location lookups and field translation.
Forecast availability is determined by your content licensing agreement with TWC. Core Package subscribers receive shorter-range forecasts; Enhanced Forecast Package subscribers receive extended 15-day access. Each time segment duration is an atomic endpoint — your API key must be authorized for the specific duration requested.

Domain Capabilities

Standard Forecasts
Daily Forecast provides day/night/24-hour summary forecasts for 3, 5, 7, 10, or 15 days. Each day includes up to three forecast segments: day (7am–7pm), night (7pm–7am), and a 24-hour summary. The temperatureMax field and daypart index 0 fields return null after 3pm local time. The forecast transitions at 3am local time. Hourly Forecast provides hour-level forecasts for 2-day (Core) or 15-day (Enhanced) durations. Hourly Forecast Enterprise extends this with additional granularity at 6-hour, 12-hour, 1, 2, 3, 10, and 15-day durations with advanced meteorological fields. Intraday Forecast breaks each day into four 6-hour segments (Morning, Afternoon, Evening, Overnight) for 3, 5, 7, or 10 days. 15-Minute Forecast provides up to 28 forecast periods in 15-minute increments over 7 hours. All standard forecasts support geocode, IATA, ICAO, Place ID, and postal key lookups.
Precipitation & Timing
Precipitation Forecast returns onset and offset times for rain, snow, sleet, and freezing rain events across 28 time steps over 7 hours. Events are weather-based rather than time-period-based — transitions between dry, cloudy, and precipitation states each generate separate records. When Will It Rain provides a simplified 6-hour precipitation timing forecast with customizable Mustache-style template expressions. Both support geocode and location ID lookups.
Probabilistic Forecasts
Probabilistic Hourly Forecast generates statistical forecast content on the fly, including discretized PDFs, probability integrations over value ranges, percentile extractions, and prototypes. Hourly data starts at the current hour and extends from 24 to 360 hours (default 240). Hourly temperature distributions are enhanced using BMA calibration, though calibration is not available for min/max/sum aggregations or non-temperature parameters.
Climatology & Seasonal
Climatology Averages provides monthly aggregates from 30 years of ERA-5 observation data (1991–2020) at 0.25-degree resolution (27 km), delivered as Tiler, Featurizer, and point data products. Seasonal & SubSeasonal Forecast predicts monthly or three-monthly (seasonal) and weekly (subseasonal) departures from normal at 40-km resolution. Seasonal input data refreshes up to three times per month; all forecasts are re-published every 24 hours.
Astronomy
Returns sunrise/sunset times, moonrise/moonset times, and moon phase data for 1, 5, 7, 15, or 30-day periods. Supports geocode, IATA, ICAO, Place ID, and postal key lookups.
Tidal Predictions
U.S. Tidal Predictions provides marine tide forecasts for coastal locations in the US and its territories, derived from harmonic and subordinate tide stations. Data covers 12 months prior through 12 months forward. Returns no data for locations more than 60 miles from the coastline. Available in 3, 5, 10, 15-day and monthly durations.
Gridded Forecast Visualization
Forecast - 15 Day Gridded & Polygonal delivers forecast data as Tiler and Featurizer products, including gFOD (4-km), Radar Model Blend precipitation, temperature, wind, atmospheric parameters, and specialized indices. Temporal resolution ranges from 15-minute to 24-hour intervals. Global Lightning Forecast provides NOWRad-derived lightning strike density (flash/km² over 30 minutes) across Global Radar Tiles 1–8 at 1-km resolution, refreshed every 5 minutes.
Radar-Derived Products
A suite of Tiler + Featurizer products derived from radar data at 1-km resolution. HailVision provides aggregate maximum hail size (mm) across 30-minute through 24-hour windows for CONUS and Canada. HailZone provides 30-minute hail size forecasts for the US, Canada, and Australia. RainVision, SnowVision, and IceVision provide aggregate accumulation (mm) across 1 through 24-hour windows for CONUS and Canada. ShearVision provides rotational shear measurements (Hz) for the lowest 2 km of atmosphere over 1-hour windows for CONUS and Canada.
Lifestyle Indices
Golf Index rates golfing conditions based on weather factors, available in daypart (up to 15 days) and hourly (up to 360 hours) intervals. Running Weather Index rates outdoor running conditions for both short and long runs at the same intervals. Ski Index rates skiing conditions in daypart intervals (up to 15 days). Stargazing Index provides hourly suitability scores for stargazing for 1 or 2-day durations. All indices support geocode and postal code lookups with translated category fields.

API Collection

1. 15-Minute Forecast: Up to 28 periods in 15-min increments over 7 hours
2. Daily Forecast: 3, 5, 7, 10, or 15-day day/night/summary forecasts
3. Hourly Forecast: 2-day or 15-day hourly forecasts
4. Hourly Forecast - Enterprise: 6-hour through 15-day hourly forecasts with advanced fields
5. Intraday Forecast: 3, 5, 7, or 10-day forecasts in 6-hour segments
6. Precipitation Forecast: Event-based precipitation onset/offset over 7 hours
7. When Will It Rain: 6-hour precipitation timing with template expressions
8. Probabilistic Hourly Forecast: Statistical forecast content (PDFs, percentiles, probabilities) for 24–360 hours
9. Astronomy: Sunrise/sunset, moonrise/moonset, and moon phases for 1–30 days
10. U.S. Tidal Predictions: Coastal tide forecasts in 3–15 day and monthly durations (US & Caribbean)
11. Climatology Averages: 30-year ERA-5 monthly aggregates (Tiler + Featurizer + Point Data)
12. Seasonal & SubSeasonal Forecast: Monthly/weekly departure-from-normal predictions at 40-km resolution (Tiler + Featurizer + Point Data)
13. Forecast - 15 Day Gridded & Polygonal: gFOD, RMB, and specialized forecast layers (Tiler + Featurizer, limited availability)
14. Global Lightning Forecast: NOWRad lightning density forecast at 1-km resolution (Tiler + Featurizer)
15. HailVision: Aggregate max hail size, 30-min to 24-hour windows (Tiler + Featurizer, CONUS/Canada)
16. HailZone - 30 Minute: 30-min hail size forecast (Tiler + Featurizer, US/Canada/Australia)
17. RainVision: Aggregate rain accumulation, 1 to 24-hour windows (Tiler + Featurizer, CONUS/Canada)
18. SnowVision: Aggregate snow accumulation, 1 to 24-hour windows (Tiler + Featurizer, CONUS/Canada)
19. IceVision: Aggregate ice accumulation, 1 to 24-hour windows (Tiler + Featurizer, CONUS/Canada)
20. ShearVision - 1 Hour: Rotational shear in lowest 2 km (Tiler + Featurizer, CONUS/Canada)
21. Golf Index: Golfing conditions in daypart and hourly intervals
22. Running Weather Index: Running conditions (short/long run) in daypart and hourly intervals
23. Ski Index: Skiing conditions in daypart intervals
24. Stargazing Index: Stargazing suitability in hourly intervals (1–2 days)