Multi-Model Weather Ensemble Forecast API
Pricing
Pay per usage
Multi-Model Weather Ensemble Forecast API
High-accuracy temperature and precipitation forecasts using 82-member multi-model ensemble (GFS 31 + ECMWF 51). Returns confidence intervals, percentiles, and NWS-corrected predictions. 1.8°F MAE vs ~3-4°F for single-model services.
Pricing
Pay per usage
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Developer
Stew Williamson
Actor stats
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Bookmarked
2
Total users
1
Monthly active users
8 days ago
Last modified
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Probe: Weather Ensemble Forecast API
Hypothesis
Users want higher-accuracy weather forecasts than basic single-model APIs. Our multi-model ensemble (GFS 31 + ECMWF 51 members + NWS bias correction) produces 1.8°F MAE vs ~3-4°F for single-model services. Existing Apify weather actors are thin wrappers around Open-Meteo (single model). A multi-model ensemble with confidence intervals is a genuine technical moat.
What
Apify Actor that provides high-accuracy temperature forecasts for US cities with confidence intervals. Input: city/zip/lat-lng + date range. Output: ensemble mean, confidence bands (10th/25th/50th/75th/90th percentile), NWS-corrected prediction, ensemble spread (uncertainty indicator).
Revenue Model
Pay-per-event on Apify Store (80% rev share):
- $0.01 per city-day forecast (includes ensemble run)
- Estimated Apify platform cost: ~$0.001/call (lightweight compute, no browser)
- Net margin: ~$0.007/call
Target Users
- Prediction market traders (Kalshi, Polymarket weather markets)
- Event planners needing high-confidence forecasts
- Agriculture/energy companies needing probabilistic weather
- AI agents that need weather data with uncertainty quantification
Technical Plan
- Extract weather pipeline from agent-gamma (ensemble.py, calibrator.py, NWS correction)
- Package as standalone Apify Actor (TypeScript wrapper or Python Actor)
- Input schema: cities[], date_range, include_hourly
- Output: structured JSON with ensemble statistics per city per day
- ≤200 LOC new code (mostly adapter around existing pipeline)
Build Cost
- Time: ≤1 session (Builder hat)
- Money: $0 (Apify free tier, all weather APIs are free)
- Dependencies: Open-Meteo API (free, no key), NWS API (free, no key)
Distribution
- Apify Store (primary — searchable as "weather forecast ensemble")
- Name: "Weather Ensemble Forecast API" or "Multi-Model Weather Forecast"
- Keywords to rank for: "weather forecast", "weather API", "temperature forecast", "weather ensemble"
- Secondary: mention in prediction market communities (Reddit r/kalshi, r/polymarket)
Kill Criteria
- 0 external Apify runs after 14 days → KILL
- Actor consistently returns errors or slow responses → FIX or KILL
Success Signal (graduation to full engine)
- ≥5 external users making repeat calls within 30 days
- OR ≥$1 cumulative revenue within 30 days
- Graduation: becomes Agent Delta, gets dedicated directory, expanded city coverage
Differentiation from Existing Weather Actors
| Feature | Existing (Open-Meteo wrappers) | Ours |
|---|---|---|
| Models | 1 (Open-Meteo default) | 82 (GFS 31 + ECMWF 51) |
| Bias correction | None | NWS-corrected (70% weight) |
| Confidence intervals | None | 10th-90th percentile |
| Accuracy (MAE) | ~3-4°F | ~1.8°F (backtested) |
| Per-city calibration | No | Yes (sigma multipliers) |
Risks
- Free weather data (Open-Meteo, NWS) may be "good enough" for most users
- Ensemble computation adds latency vs simple API passthrough
- Apify Store discovery problem (same as Alpha) — mitigated by keyword-optimized naming

