Onrus Beach is popular for both swimming and surfing, though conditions vary. The beach offers sandy entry points suitable for swimming, particularly where the Onrus River meets the sea, creating calmer lagoon-like areas favored by families. However, the beach is not lifeguarded, so swimmers must be cautious of currents and changing conditions. Surfers appreciate the consistent waves, especially during southwest swells. Beginners should surf during smaller swell days and be aware of rip currents. The mix of activities means swimmers and surfers should respect each other's space. Cold water temperatures year-round require wetsuits for extended water time.

Onrus Beach is best visited during the summer months (November to March) when weather is warmest and most reliable for beach activities and sunbathing. This period offers the most consistent sunny days and calmer seas for family swimming. For surfing, autumn and winter (April to August) often bring better swells, though water is colder. Budget travelers can find better accommodation rates during shoulder seasons (April-May, September-October) with still-pleasant weather. Weekdays throughout the year are less crowded than weekends. Early mornings offer the calmest conditions and beautiful light, while late afternoons can bring stronger onshore winds.