The short answer is yes, it will be very safe. Why? The beach has wind, sun, the salty spray in the air, and people spread out. Let’s consider each of these separately.
Wind. Because the water of the ocean and the adjacent land have very different responses to the warming effect of the sun there is an almost constant wind at the beach. Is that good or bad for spreading SARS-CoV-2? A nice study 1 (not peer-reviewed however) looked at the rate of COVID-19 cases and various weather conditions in four cities in China and five locations in Italy. They then plotted wind speed versus the number of cases (because of the average five day incubation period they correlated cases and weather with a five day interval). In eight of the nine cities the higher the wind speed the lower the rate of cases. The effect was not huge but in the vast majority of the time, the more wind the fewer cases. So given that effect, being at a windy beach versus a still air part of town away from the beach, will have fewer cases.
Sun and temperature. Previous results on the relationship between respiratory-borne infectious diseases and temperature have indicated that both SARS and influenza need to survive under certain temperature conditions, and increasing temperature can reduce their ability to spread. The underlying hypothesis as to why warmer seasons tend to decrease the spread of viruses include: higher vitamin D levels, resulting in better immune responses; increased UV radiation; and no school in the summer (when children are clustered together, transmission rates of flu and measles increase). Reports of UV and respiratory diseases have also been considered, and previous studies have shown that high levels of UV exposure can reduce the spread of SARS-CoV virus.
However, in this study of UV exposure and COVID-192 which had a six-fold difference in UV radiation there was no effect of increasing UV. With respect to temperature, the first study1 showed a positive effect, with each increase in temperature of one degree having a 1% decrease in COVID-19 incidence. The second study, however, saw no temperature effect.
Salty spray. The spray from the ocean, the aerosol, contains water, salt, and lots of ocean microbes.3 Importantly, they also contain a large and diverse collection of fatty acids, those long carbon chain chemicals we all know commonly as soaps. If a human sneeze/cough/breath droplet were to merge with a sea aerosol and then it began to float on the wind two things would happen: as it ‘dried’ in the air the salt concentration would increase, and the fatty acids would attack the membrane of the envelope virus, SARS-CoV-2. Both of these actions would quickly destroy the virus! This will not happen with fresh water lakes, by the way.
Public bathrooms. Even before COVID-19 the public facility situation at the beach is far from ideal. Nothing special for COVID-19 here. Just wash your hands after and if you are really talented, hold your breath if you can!
Get even more tips on staying safe with COVID-19 by following my blogs at ElevatorMedicine or get my new book on Amazon Kindle, Your COVID-19 Survival Manual: A Physician’s Guide to Keep You and Your Family Healthy During the Pandemic and Beyond.