Overview
The dashboard combines data from three sources to assess whether conditions are suitable for swimming, kayaking and stand-up paddleboarding (SUP) at Littlehampton Beach. It looks at each hour of the day and identifies the best time windows for each activity.
This is automated guidance only. Always check conditions on arrival and use your own judgement.
Data Sources
- Weather forecast (wind, temperature, rain, visibility, sunrise/sunset) — Open-Meteo, sourced from ECMWF, DWD, Met Office and other national weather services.
- Marine forecast (wave height, wave period, swell, sea temperature) — Open-Meteo Marine API, sourced from Copernicus Marine Service.
- Tidal predictions (high/low water times and heights) — ADMIRALTY UK Tidal API for Littlehampton (Station 0074). Crown copyright and database right.
- Live wave conditions (real-time wave height, period, sea temperature) — Regional Coastal Monitoring Programme, Rustington wave buoy. Not quality-controlled.
- Live weather (real-time air temperature, wind speed, gusts, direction) — Regional Coastal Monitoring Programme, Worthing Pier met station. Not quality-controlled.
- Storm overflow discharges (sewage discharge alerts) — National Storm Overflow Hub, Southern Water near-real-time event data via ArcGIS. Updated within ~1 hour of discharge events.
Sewage Discharge Alerts
The dashboard monitors storm overflow outfalls near Littlehampton for sewage discharge events. These are informational only and do not change the activity scoring.
What we monitor
Outfalls are grouped by how they affect the beach:
- Coastal outfalls — discharge directly into the English Channel near the beach. Immediate impact on water quality.
- River Arun outfalls — discharge into the River Arun upstream. The Arun flows into the sea at Littlehampton Harbour, so upstream discharges can affect beach water quality, particularly on an outgoing (ebb) tide which carries river water seaward.
- Tributary outfalls — discharge into local waterways (Black Ditch, Ryebank Rife, Ferring Rife, etc.) which may eventually reach the coast.
Alert levels
- Active discharge (red) — one or more storm overflows are currently discharging. The alert describes which type of outfall is active. Avoid entering the water.
- Recent discharge (amber) — a discharge ended within the last 48 hours. Water quality may still be affected.
- Clear (green) — no discharges reported in the last 48 hours.
Data is from Southern Water’s Event Duration Monitors via the National Storm Overflow Hub. This is unverified operational data, updated within approximately 1 hour of events, and may have gaps or delays.
Activity Scoring
Each hour during daylight is scored as good, fair or poor for each activity. The thresholds are:
| Factor | Swimming | Kayaking | SUP |
|---|---|---|---|
| Wave height — poor | > 1.0 m | > 0.7 m | > 0.5 m |
| Wave height — fair | > 0.5 m | > 0.3 m | > 0.3 m |
| Wind speed — poor | > 20 kn | > 18 kn | > 15 kn |
| Wind speed — fair | > 15 kn | > 12 kn | > 10 kn |
| Wind gusts — poor | — | > 25 kn | > 20 kn |
| Wind gusts — fair | — | > 18 kn | > 15 kn |
| Precipitation — poor | > 4 mm/h | > 4 mm/h | > 3 mm/h |
| Precipitation — fair | > 1 mm/h | > 1 mm/h | > 0.5 mm/h |
Tide Impact
Tidal state is calculated for each hour based on proximity to Admiralty high/low water predictions.
- Low tide (within ±1 hour of low water) — downgrades kayak and SUP by one level (good → fair, fair → poor). Swimming is also downgraded at low tide. At Littlehampton, low tide exposes shallow water and can make launching difficult.
- Near low tide (within ±2 hours) — downgrades kayak and SUP by one level.
- High tide and rising/falling — no penalty. Generally the best conditions for all watersports, with more water depth and better access.
When a time window is shown, the dashboard also notes its relationship to high tide (e.g. “around high tide 10:34”) for kayak and SUP.
Time Windows
Rather than a single rating for the whole day, the dashboard finds the best contiguous period of good or fair hours during daylight:
- All day — conditions are suitable for nearly all daylight hours.
- From HH:00 — conditions improve from that time until sunset.
- Until HH:00 — conditions are suitable from sunrise until that time.
- HH:00–HH:00 — a specific window during the day.
- Avoid — [reason] — no usable window found, with the dominant reason (high waves, strong wind, heavy rain, or low tide).
Minimum window: 1 hour for swimming, 2 hours for kayak and SUP.
Daylight
Activities are only scored during daylight hours. Sunrise and sunset times are shown on each day card. Hours before sunrise or after sunset are excluded from the usable window.
Wetsuit Recommendations
Based on sea surface temperature, with a wind-chill adjustment (if wind exceeds 15 knots, the effective temperature is shifted down by 2°C, recommending one grade thicker):
| Sea Temperature | Recommendation |
|---|---|
| > 20°C | Boardshorts / swimsuit |
| 18–20°C | Rash vest + boardshorts |
| 16–18°C | Shorty wetsuit |
| 14–16°C | 3/2mm spring suit |
| 12–14°C | 3/2mm full wetsuit |
| 10–12°C | 4/3mm wetsuit + boots |
| 8–10°C | 5/4mm + boots & gloves |
| < 8°C | 5/4mm + hood, boots & gloves |
UV Index & Sun Protection
When the peak UV index during daytime hours reaches 3 or above, a suncream recommendation is shown alongside the wetsuit suggestion. Remember that UV reflects off water, increasing exposure.
| Peak UV Index | Recommendation |
|---|---|
| 0–2 | No suncream needed |
| 3–5 (Moderate) | SPF 30 suncream |
| 6–7 (High) | SPF 50 suncream |
| 8+ (Very High) | SPF 50+ suncream, seek shade |
Limitations
- Forecast data is model-based and may not reflect actual conditions. Always verify on arrival.
- Wave data is from an offshore model — inshore conditions at Littlehampton (inside the harbour, river mouth) may differ significantly.
- Tidal predictions are for standard port Littlehampton — actual water levels can vary due to weather, atmospheric pressure and river flow.
- Live wave data from the Rustington buoy and weather data from Worthing Pier are not quality-controlled and may have gaps or errors.
- The scoring algorithm is a simplified guide. It does not account for local hazards, currents, visibility, user experience level, or specific launch conditions.
- This forecast is not suitable for navigation.