Sunny, high near 90°. Rain chance peaks at 45% around 2 PM. Best beach window: 8 AM to 2 PM.
estimateRain Outlook
tap an hourPeak rain chance 45% around 2 PM — plan beach time outside that window.
Tide
0.3 ft · falling ↘
Wind
11 mph
from the E
UV Index
Very High
reapply every 80 min
Time to Burn
UV 10 · incl. sand glarefor unprotected fair skin (burns easily, tans a little). SPF 50, reapply every 80 minutes and after every swim.
Strongest 9 AM to 6 PM · peaks at UV 10
An estimate from the standard erythemal dose model, not a medical limit. Darker skin burns more slowly than this, people vary either way, and sunscreen only helps if you use enough of it and reapply.
Rip Current Riskestimated
todayCalm pattern today. Currents can still surprise — keep kids within reach.
Caught in one? Don’t fight it. Swim parallel to the beach until you’re free, then angle back in.
Beach Flag
Green Flag
calm, swim easy
estimated · trust the lifeguard
Water Quality
bacteria testingHalf Moon Bay has been posted or closed for bacteria 344 times since 2022.
This is history, not today. The state archive runs months behind (through 2026-03-06), so check the county for the current posting.
Today’s official resultSource: Health Department County of San Mateo Environmental Health
Water by Monthtypical
avg 2021–2024Warmest around September (60°), coolest around April (53°).
surf’s up (gently)
Tides are NOAA predictions (Half Moon Bay State Beach station 9414290); temps, wind, UV, waves and water temp are live from Open-Meteo; rip current risk from the NWS surf-zone forecast. Flag status is estimated from wave height and wind, so always trust the lifeguard’s actual flag over this app.
Right now at Half Moon Bay, the water is 61°F, surf is running 3–4 ft and the air is 61°F. Wind is 8 mph from the S and the UV index peaks at 6 (high) today. Unprotected fair skin burns in about 240 minutes right now, and the strongest stretch runs 3 PM to 4 PM. Today’s tides: High 5:52 AM, Low 9:55 AM, High 4:02 PM, Low 11:26 PM. Half Moon Bay State Beach has been posted or closed for bacteria 344 times since 2022, about 68.8 a year. Dogs are not allowed on this beach.