May in Arona, Spain, brings average daily highs of 19°C and overnight lows of 15°C in the 2016–2025 historical record. Pack clothes you can layer as conditions change. The average leaves room for both warmer and cooler days, so a flexible walking plan is more useful than deciding every outdoor stop before you arrive.
In the record, at least 1 mm of rain or snow falls on 2 of 31 days on average, a daily chance of 5%. Rain has been relatively infrequent in this record, which leaves more scope for an outdoor plan. Still keep an alternative for a wet day: a low monthly average cannot tell you when the rain will arrive.
The calculated day length, sunrise to sunset, averages about 14 hours. Sunshine averages 13 hours a day. The longer daylight window gives you more choice about when to be outside; it does not mean every part of the day will be sunny. Sunshine is a separate measure, and those hours need not arrive in one uninterrupted stretch.
For nature trips or walks, keep the longest outings movable and check route conditions locally; a monthly climate average cannot establish whether a particular path is accessible. If the coast is part of your plan, check water conditions separately. Air temperature and sunshine do not establish swimming conditions, surf quality or diving visibility.
June has an average daily high of 21°C, 2°C higher than May. Its historical rain-day chance is 3%, compared with 5% this month. If your dates are flexible, compare those trade-offs with the kind of days you want. Neither set of averages predicts the conditions of one particular holiday.