Nippy Index — Sea Swim Conditions

NippyIndex

Before you search

The conditions shown here are calculated by this tool from third-party forecast models, not measured at each location, and can be incorrect or understate what is actually happening. Open water can change fast and without warning.

Nippy Index is an assessment of physical conditions only - not a safety rating
Always make your own assessment before entering the water
This is not a substitute for official forecasts, warnings or lifeguard advice - check local signs and current alerts
A location appearing here does not mean it is safe, accessible or suitable for any activity
The Nippy Index describes conditions only. It does not rate or imply safety, and does not account for your individual ability

I have read and understand the above

How's the water today?

Current conditions data for UK seas, lakes, lochs and reservoirs

The conditions here come from forecast models — not readings taken directly at each location. They could be incorrect or understate actual conditions. Open water can change fast and without warning.

Always make your own assessment
Check for local signs, warnings or advice
A location appearing here does not mean it is safe, accessible or suitable for any activity
The Nippy Index describes conditions only. It does not imply any level of safety.

Typical Waves

estimate

Larger Waves

estimate

Largest Sets

estimate
over 30 minutes

Water

Air

Feels Like

Wind Speed

Wind Direction

Relative Wind

Water Quality

Wave Period

Wave Type

Water Quality

Moonrise

Moonset

Illumination

Sunrise

Sunset

Inland swimming - things to be aware of

Cold water at depth - Lakes and lochs are significantly colder below the surface thermocline. Even in summer the deep water may be near 4°C. Never dive headfirst.
Submerged vegetation - Weeds and reeds can entangle swimmers, particularly near shallow margins. Stay clear of dense surface growth.
Boat traffic - Be visible and aware of powerboats, sailing vessels and jet skis, especially on popular lakes and reservoirs.
Leptospirosis (Weil's disease) - Risk is elevated near river inflows, areas with obvious rat activity, or stagnant margins. Any cuts or abrasions should be covered before water contact.

Blue-Green Algae - Where to find alerts

Blue-green algae (cyanobacteria) blooms are most common in warm, calm, nutrient-rich water during summer months. Water may look green, blue-green or brownish with a paint-like scum. Toxins can cause skin rashes, vomiting, and in serious cases liver damage. Always check for current alerts, regardless of what this tool shows.

Check current advisories:
🏴󠁧󠁢󠁥󠁮󠁧󠁿 England — gov.uk: Lake Bathing Water Quality
🏴󠁧󠁢󠁥󠁮󠁧󠁿 England — EA Swimfo: Designated Bathing Waters
🏴󠁧󠁢󠁳󠁣󠁴󠁿 Scotland — SEPA: Where Can I Swim
🏴󠁧󠁢󠁷󠁬󠁳󠁿 Wales — Natural Resources Wales

Today's Tidal Curve

Hourly Nippy Index

Hourly bars · sunrise to sunset
■ Low ■ Moderate ■ Elevated+

Shoreline Wave Height Estimate

Darker base = typical waves · lighter top = larger waves
■■ Low ■■ Moderate ■■ Elevated

Predicting the wave height can be difficult, and these figures should be used only as a guide. They are based on buoy data several miles offshore, which gauge the average height and are then adjusted to account for energy loss as waves approach the shore. However, waves behave differently depending on beach shape, tide level, wind, and other conditions.

Wave Force

Relative wave energy from forecast models (estimate). Hourly bars · sunrise to sunset
■ Low ■ Moderate ■ High

Air Temperature & Weather

Hourly forecast · °C

Rainfall

Hourly forecast · mm per hour

Forecast precipitation only. Heavy or persistent rainfall can increase water quality risk near river mouths, storm drains, and estuaries. Check the SAS Safer Seas Service for sewage alerts.

Today's Tides

Loading tide data...

Hourly Nippy Index

Hourly bars · sunrise to sunset
■ Low ■ Moderate ■ Elevated+

Shoreline Wave Height Estimate

Darker base = typical waves · lighter top = larger waves
■■ Low ■■ Moderate ■■ Elevated

Wave Force

Relative wave energy from forecast models (estimate). Hourly bars · sunrise to sunset
■ Low ■ Moderate ■ High

Air Temperature & Weather

Hourly forecast · °C

Rainfall

Hourly forecast · mm per hour

Forecast precipitation only. Heavy or persistent rainfall can increase water quality risk near river mouths, storm drains, and estuaries. Check the SAS Safer Seas Service for sewage alerts.

Tomorrow's Tides

Loading tide data...

Peak Nippy Index

AM (6am–noon) and PM (noon–6pm) peak score
■ Low ■ Moderate ■ Extreme

Shoreline Wave Height Estimate

Darker base = typical waves · lighter top = larger waves
■■ Low ■■ Moderate ■■ Elevated

Wave Force Estimate

Relative wave energy from forecast models (estimate). Hourly bars · sunrise to sunset
■ Low ■ Moderate ■ High

7-Day Air Temperature & Weather

Daily maximum °C

7-Day Rainfall Forecast

Daily total precipitation (mm)
■ Light ■ Moderate ■ Heavy

Forecast precipitation only. Heavy or persistent rainfall can increase water quality risk near river mouths, storm drains, and estuaries. Check the SAS Safer Seas Service for sewage alerts.

Water Quality Risk (Rainfall-based)

Based on forecast rainfall in the 48 hours prior to each day
■ Low ■ Moderate ■ High

Risk is estimated from forecast precipitation only and does not account for CSO discharges, river levels, or local drainage. Always check the SAS Safer Seas Service for sewage alerts.