Rough water today
forecastNo weather alert for Half Moon Bay State Beach, but the forecast has waves to 7 ft. Fine for a walk, not for a swim.
Rough water today. Overcast, high near 65°. No real rain risk. Driest stretch: all day, but dry isn't calm. Keep out of rough water.
forecastRain OutlookOpen-Meteo
tap an hourTop rain chance is just 2%, but dry doesn't mean calm today. See the surf and wind above.
Tide
0.3 ft · falling ↘
Next low tide
12:24 PM 0.2 ft
T−…
1.9 ft of drop from the 7:54 AM high; the wet sand is widest from about 11:24 AM.
Wind
5 mph
from the SW
UV Index
Moderate
easy sunscreen day
Time to Burn
UV 3 · incl. sand glarefor unprotected fair skin (burns easily, tans a little). SPF 30 if you are out for more than an hour.
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
todayDangerous currents likely. Knee-deep only, lifeguarded sand only.
Caught in one? Don’t fight it. Swim parallel to the beach until you’re free, then angle back in.
Beach Flag
Red Flag
knee-deep only
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.
Rough water today. No weather alert for Half Moon Bay State Beach, but the forecast has waves to 7 ft. Fine for a walk, not for a swim. The water at Half Moon Bay State Beach is 64°F (18°C) today, 9°F warmer than the usual 55°F for November. For swimming it is chilly: bracing for most people, and a wetsuit helps. Waves are 6–7 ft (very rough). The air is 64°F, feeling like 61°F, with light 4 mph winds from the SW. The UV index reaches 3 (moderate).
The water holds steady around 64°F through Sun Nov 8.
The week ahead at Half Moon Bay State Beach, day by day: the sky, the high, the strongest wind and the biggest waves, the UV peak and the daytime chance of rain, and the water temperature. The calmest day for a swim looks like Mon Nov 2.
| Day | Sky | High | Wind | Waves | UV | Rain | Water |
|---|---|---|---|---|---|---|---|
| Today | Cloudy | 65°F | 8 mph | 6.9 ft | 3 | 1% | 64°F |
| Tue Nov 3 | Rain | 64°F | 15 mph | 8.7 ft | 4 | 56% | 64°F |
| Wed Nov 4 | Cloudy | 66°F | 13 mph | 8.7 ft | 4 | 4% | 64°F |
| Thu Nov 5 | Cloudy | 70°F | 8 mph | 7.8 ft | 4 | 1% | 64°F |
| Fri Nov 6 | Cloudy | 76°F | 8 mph | 9.2 ft | 4 | 0% | 64°F |
| Sat Nov 7 | Mostly sunny | 77°F | 5 mph | 9.4 ft | 4 | 0% | 64°F |
| Sun Nov 8 | Cloudy | 78°F | 7 mph | 7.7 ft | 4 | 0% | 64°F |
High and low tides for the next 7 days, from NOAA’s predictions for tide station 9414290. Heights are in feet above the average low tide. The shell window is the last hour and a quarter of the ebb and the first three-quarters of the flood around the day’s lowest daylight low, when the most sand is bare; the lowest low of the week is marked.
| Day | Tide 1 | Tide 2 | Tide 3 | Tide 4 | Shell window |
|---|---|---|---|---|---|
| Today | High 6:35 AM 5.0 | Low 11:51 AM 2.7 | High 5:21 PM 5.0 | — | 10:36 AM–12:36 PM |
| Tue Nov 3 | Low 12:06 AM 0.1 | High 7:21 AM 5.3 | Low 1:01 PM 2.1 | High 6:43 PM 4.8 | 11:46 AM–1:46 PM |
| Wed Nov 4 | Low 1:00 AM 0.5 | High 8:00 AM 5.6 | Low 1:59 PM 1.4 | High 7:57 PM 4.7 | 12:44 PM–2:44 PM |
| Thu Nov 5 | Low 1:47 AM 0.9 | High 8:35 AM 5.9 | Low 2:48 PM 0.7 | High 9:03 PM 4.7 | 1:33 PM–3:33 PM |
| Fri Nov 6 | Low 2:29 AM 1.3 | High 9:08 AM 6.1 | Low 3:32 PM 0.2 | High 10:03 PM 4.7 | 2:17 PM–4:17 PM |
| Sat Nov 7 | Low 3:09 AM 1.8 | High 9:38 AM 6.2 | Low 4:11 PM -0.2 | High 10:58 PM 4.7 | 2:56 PM–4:56 PM |
| Sun Nov 8 | Low 3:47 AM 2.3 | High 10:06 AM 6.2 | Low 4:48 PM -0.4 | High 11:50 PM 4.7 | 3:33 PM–5:33 PM · best |
The average sea temperature at Half Moon Bay State Beach for each month (2021–2024). The water is warmest in September (60°F) and coolest in April (53°F). It never averages 74°F, so most swimmers use a wetsuit.
| Month | Water °F | Water °C | For swimming |
|---|---|---|---|
| January | 55°F | 13°C | Cold |
| February | 55°F | 13°C | Cold |
| March | 54°F | 12°C | Cold |
| April | 53°F | 12°C | Cold |
| May | 54°F | 12°C | Cold |
| June | 56°F | 13°C | Cold |
| July | 57°F | 14°C | Cold |
| August | 58°F | 14°C | Cold |
| September | 60°F | 15°C | Cold |
| October | 59°F | 15°C | Cold |
| November (now) | 55°F | 13°C | Cold |
| December | 55°F | 13°C | Cold |
Rip currents. If a current pulls you away from shore, don’t fight it: swim parallel to the beach until you are out of it, then swim back in. If you can’t, float and wave for help.
Sun. The UV index peaks at 3 today. Wear SPF 30 and reapply every two hours and after swimming.
Water quality. Half Moon Bay State Beach has been posted or closed for bacteria 344 times since 2022, about 68.8 a year. Official sampling results →
Dogs. Dogs are not allowed on this beach.
Swim near a lifeguard when one is on duty, and follow the beach flags and posted signs. The Half Moon Bay State Beach rules page covers dogs, alcohol, fires and more.
Under 1 ft is calm, good for small children and floating. 1–2 ft is small, fine for most swimmers. 2–4 ft is moderate: fun for bodyboarding, harder for weak swimmers. 4–6 ft is rough, and over 6 ft is dangerous for swimming. Today at Half Moon Bay State Beach it’s very rough.
Under 8 mph is light and pleasant. 8–15 mph is breezy, good for kites and cooler on a hot day. 15–25 mph blows sand and whips up the water. Over 25 mph most people pack up. Today at Half Moon Bay State Beach it’s light.
0–2 is low, 3–5 moderate, 6–7 high, 8–10 very high and 11 or more extreme. At 8 or more, fair skin can burn in under 20 minutes. The UV index is highest around midday even when it is cloudy.
Under 60°F is cold and most people want a wetsuit. 68–73°F is cool but swimmable. 74–79°F feels comfortable, and 80°F or more feels warm.
64°F (18°C), 9°F warmer than the usual 55°F for November.
At 64°F the water is chilly: bracing for most people, and a wetsuit helps. Waves are 6–7 ft, which is very rough.
6–7 ft, which is very rough. The wind is 4 mph from the SW.
High tide is at 6:35 AM and 5:21 PM, and low tide is at 11:51 AM. Times are NOAA predictions.
The UV index peaks at 3 (moderate). Wear SPF 30 and reapply every two hours and after swimming.
Highs run 64–78°F over the next 7 days. Rain is likely on Tue Nov 3. The calmest day for a swim looks like Mon Nov 2.
The water at Half Moon Bay State Beach averages about 55°F (13°C) in November.
September is the warmest month, averaging 60°F. April is the coolest, at 53°F.
The water never averages 74°F here. It is warmest in September, at 60°F, so bring a wetsuit most of the year.
The usual water temperature in November at the nearest beaches. Tap one for its live conditions.
| Ocean Beach San Francisco conditions | 18 mi | 56°F |
|---|---|---|
| Baker Beach conditions | 21 mi | 56°F |
| Muir Beach conditions | 26 mi | 56°F |
| Stinson Beach conditions | 30 mi | 56°F |
| Santa Cruz Beach conditions | 44 mi | 56°F |
| Capitola Beach conditions | 46 mi | 56°F |
More for Half Moon Bay State Beach: parking · sunset time tonight · things to do · US water temperatures today →