Contents
1. Terms of Use
By accessing or using AerisCast ("the Service"), you agree to these terms. If you do not agree, do not use the Service.
Use of the service
- AerisCast is provided for personal, non-commercial use on the free plan.
- AerisPro subscribers may use the Service for personal and professional purposes.
- You may not reverse engineer, resell, or redistribute forecast data obtained from AerisCast.
- Automated scraping of forecast data is not permitted.
Changes to the service
AerisCast reserves the right to modify, suspend or discontinue any part of the Service at any time. Paid subscribers will be given reasonable notice of any material changes that affect their subscription.
Contact
For questions or concerns: [email protected]
2. Forecast Disclaimer
Weather forecasting is inherently uncertain. All forecasts degrade in accuracy with time and are subject to change as new model data becomes available. AerisCast makes no warranty, express or implied, regarding the accuracy, completeness, or timeliness of any forecast.
AerisCast and its operators accept no liability for any loss, damage, injury or decision made in reliance on forecast data provided by this service.
For safety-critical decisions, always consult your national meteorological authority.
3. Model Limitations
AerisCast uses two numerical weather prediction models — ECMWF IFS (via MET Norway) and NOAA GFS (via Open-Meteo). Both are global models with inherent physical and computational limitations users should be aware of.
Spatial resolution
ECMWF IFS operates at approximately 9km horizontal resolution; GFS at approximately 13km. This means the models represent grid-cell averages, not exact point conditions. Terrain features smaller than the grid size — valleys, ridgelines, coastal cliffs, urban heat islands — are not resolved. Forecasts in complex terrain (mountains, coastlines, cities) may differ significantly from actual conditions at a specific point.
Temperature inversions
Global models frequently mishandle temperature inversions — conditions where temperature increases with altitude rather than decreasing. This affects:
- Snow level calculations — the 2°C isotherm used to estimate snow level may be inaccurate when a surface inversion is present, potentially showing an unrealistically high snow level even when snow is falling at the surface.
- Surface temperature — valley frost and fog situations driven by cold air pooling are poorly captured at global model resolution.
- Fog and low cloud — radiation fog, sea fog and inversion-capped stratus are frequently underforecast or mistimed.
Convection and thunderstorms
Neither GFS nor ECMWF can resolve individual thunderstorm cells at their native resolution. Convective forecasts (storm potential, CAPE, CIN) indicate atmospheric environments favourable for convection, not precise storm timing or location. A "high storm potential" environment may produce no storms if a triggering mechanism is absent, and conversely, a marginal environment may produce intense convection in certain terrain or boundary conditions.
Precipitation phase
The rain/sleet/snow phase determination in AerisCast is based on near-surface air temperature thresholds (snow <2°C, sleet 2–3°C, rain >3°C). This is a simplified approach. Actual precipitation phase depends on the full depth of the atmospheric column and can differ from the surface temperature alone, particularly in transitional situations near the freezing level.
Snowfall accumulation
Snowfall accumulation figures are model-derived and do not account for wind redistribution (drifting), compaction, or liquid equivalent differences between snow types. Accumulations in exposed or sheltered terrain may differ substantially from model output.
Flash flood risk
See the dedicated section below.
Forecast range and reliability
- 0–48 hours: Generally reliable for temperature, wind and precipitation type
- 2–5 days: Useful for planning but significant uncertainty in timing and amounts
- 6–10 days: Broad pattern guidance only — specific values unreliable
- 10+ days (GFS): Climatological guidance only — treat with caution
4. Flash Flood & Snow Risk Warnings
The AerisFlood tab provides a simplified flash flood risk assessment based on rainfall rate, accumulation and soil moisture proxy variables. This is not a hydrological flood model. It cannot account for:
- Local catchment characteristics, drainage capacity or soil type
- Antecedent rainfall and catchment wetness beyond what Open-Meteo soil moisture provides
- Urban drainage infrastructure and stormwater capacity
- River channel geometry or floodplain extent
- Dam operations or managed water releases
For flood warnings and emergency information, always consult your national meteorological authority and local emergency services.
Similarly, AerisSnow snow accumulation and quality ratings are derived estimates and should not be used for avalanche risk assessment or backcountry travel decisions.
Aeris Storm
Aeris Storm storm potential ratings are derived from atmospheric instability parameters (CAPE, CIN, lifted index, precipitable water and freezing level height) sourced from the GFS global model at approximately 13km resolution. These ratings reflect the atmospheric environment for storm development — not a guarantee that thunderstorms, hail, damaging winds or flash flooding will occur.
Convective initiation, storm organisation and severe weather occurrence depend on local triggers, orography and boundary-layer processes that cannot be resolved at global model scale. Hail, wind and flash flood hazard flags are indicative only. Always follow official severe weather warnings from your national meteorological authority.
5. Subscriptions & Refunds
Billing
AerisPro is billed on a recurring 3-month basis via Stripe. Your subscription renews automatically until cancelled.
Cancellation
You may cancel your subscription at any time. Access to Pro features continues until the end of the current billing period. No partial refunds are issued for unused time within a billing period.
Refunds
Refunds are issued at our discretion. To request a refund, contact [email protected].
Price changes
AerisCast reserves the right to change subscription pricing. Existing subscribers will be given at least 30 days notice before any price change takes effect.
6. Privacy & Data
AerisCast collects minimal personal data. When you create an account, your email address is stored by Clerk (our authentication provider). Payment information is handled entirely by Stripe and is never stored by AerisCast directly.
Forecast requests are routed through a Cloudflare Worker proxy. Your IP address is not forwarded to third-party weather data providers. Location coordinates used in forecast requests are passed to MET Norway and Open-Meteo as required to retrieve forecast data.
For MET Norway's privacy policy, see met.no/en/About-us/privacy. For Open-Meteo: open-meteo.com/en/terms.
We do not sell or share personal data with third parties for marketing purposes.
7. Data Attribution
AerisCast relies on the following third-party data sources:
- ECMWF IFS surface forecast data — provided by MET Norway Locationforecast 2.0 under CC BY 4.0
- ECMWF IFS upper air / atmospheric data — provided by Open-Meteo (ECMWF IFS 0.25°)
- GFS forecast and upper air data — provided by Open-Meteo (NOAA GFS Seamless)
- Elevation data — Copernicus DEM via Open-Meteo
- Geocoding and map tiles — Geoapify (OpenStreetMap contributors)
Last updated: May 2026