NZ Tides + Surf

Goal

Query live New Zealand tide and surf forecast data through a small deterministic CLI with human-readable and JSON output, without login, browser automation, account cookies, or API keys.

The main workflow is answering "is Piha worth a drive tomorrow morning?" by combining official LINZ tide predictions with SwellMap surf ratings, wave height, swell period, swell direction, and wind.

Use this when

• A user asks for tide times at a New Zealand port or surf beach
• A user asks for the next high tide or low tide
• A user asks for a surf forecast at a known NZ break
• A user wants to compare breaks in Auckland, Coromandel, Gisborne, or Wellington
• A workflow needs machine-readable tide/surf rows for trip planning

Do not use this for

• Safety-critical boating, swimming, or surf rescue decisions without checking the source sites directly
• Maritime warnings, official weather watches, or severe weather alerts
• Authenticated Surfline features, subscriptions, cameras, or personalised forecasts
• MetOcean/MetService point marine API data when an API key is available; use metservice-nz for that
• Historical tide or surf analysis beyond the published forecast/table windows

Preferred workflow

1. Run scripts/cli.py with the narrowest subcommand that answers the task
2. Use tides or next-tide for official LINZ tide predictions
3. Use surf for a specific break forecast
4. Use best-break when the user asks where to drive tomorrow morning
5. Use breaks to see the curated surf breaks and their companion LINZ tide ports
6. Use --json for agent chaining, comparisons, and reports
7. Mention that surf ratings are SwellMap forecast snapshots and tide rows are official LINZ predictions

CLI

Run with:

python3 skills/nz-tides-surf/scripts/cli.py <command> [flags]

Commands

• ports [--json] - list available LINZ tide ports and common surf aliases
• tides <port> [--date YYYY-MM-DD] [--days N] [--json] - LINZ tide predictions for a port or surf alias
• next-tide <port> [--json] - next high tide and next low tide from now
• breaks [--json] - list known NZ surf breaks and companion LINZ tide ports
• surf <break> [--days N] [--json] - SwellMap forecast for a named NZ surf break
• best-break [--region auckland|coromandel|gisborne|wgtn] [--date YYYY-MM-DD] [--json] - compare the region's morning forecast rows and pick the best average rating
• marine <area> [--json] - NIWA marine handoff note; no no-key NIWA wave endpoint was confirmed, so use metservice-nz marine for key-backed MetOcean marine data

Examples

python3 skills/nz-tides-surf/scripts/cli.py tides Auckland --date 2026-05-24
python3 skills/nz-tides-surf/scripts/cli.py tides Piha --date 2026-05-24 --json
python3 skills/nz-tides-surf/scripts/cli.py next-tide "Mt Maunganui" --json
python3 skills/nz-tides-surf/scripts/cli.py surf Piha --days 3
python3 skills/nz-tides-surf/scripts/cli.py surf Raglan --days 3 --json
python3 skills/nz-tides-surf/scripts/cli.py best-break --region auckland --json
python3 skills/nz-tides-surf/scripts/cli.py breaks

Supported surf aliases

Common surf questions are mapped to the closest practical source:

• Piha, Muriwai, Bethells, Karekare - SwellMap Auckland West Coast forecasts, LINZ Anawhata tide companion
• Raglan, Manu Bay, Raglan Bar, Mussel Rock - SwellMap Raglan forecasts, LINZ Raglan tides
• Mt Maunganui, Mount Maunganui, Tay Street - SwellMap Tay Street forecast, LINZ Moturiki Island tides
• Lyall Bay, Breaker Bay, Makara, Plimmerton - Wellington surf forecasts, LINZ Wellington tides
• Whangamata, Hot Water Beach, Kuaotunu, Whitianga - Coromandel surf forecasts, nearby LINZ tide companions

Resources

• CLI entrypoint: scripts/cli.py
• API and stability notes: references/api-notes.md
• Related key-backed marine skill: skills/metservice-nz/

Notes

• LINZ source: https://www.linz.govt.nz/products-services/tides-and-tidal-streams/tide-predictions, using https://www.linz.govt.nz/api/v1/tp and https://static.charts.linz.govt.nz/tide-tables/maj-ports/csv/....
• SwellMap source: https://www.swellmap.com/surf-forecasts/new-zealand, using the public no-login Next.js forecast payload embedded in each surf forecast page.
• MetService/MetOcean source: https://developer.metservice.com/docs/api-catalog/point-forecast-api/; the existing metservice-nz skill already covers key-backed marine/wave variables.
• NIWA source: https://niwa.co.nz; a no-key NIWA public marine wave forecast endpoint was not confirmed during implementation, so this skill does not duplicate the metservice-nz marine command.
• Surfline source investigated: https://www.surfline.com/surf-report; direct CLI requests to Surfline's public JSON/search surface returned Cloudflare challenge HTML in this environment, so SwellMap is the working no-login surf source.
• Magicseaweed is discontinued; no live Magicseaweed source is wired.
• All times are emitted in Pacific/Auckland.
• Endpoint shapes can change without notice because SwellMap and Surfline surfaces are public website implementation details rather than formal public APIs.
• Do not commit HAR captures, screenshots, cookies, raw browser profiles, or bulky JavaScript bundles when updating this skill.