From Badajoz · 38.88° N · 6.97° W
Getaways from Badajoz for 15 August: theatre nights in Mérida, Perseids at Alqueva, swimming in the lake, the Atlantic at Ericeira and the cool of the Serra da Estrela.
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In July and August the Classical Theatre Festival fills the Roman theatre in Mérida at night with Greek and Latin plays. Do the site at 9:00, before the heat, the museum in the sunny hours and buy a ticket for the performance. During the festival there may be daytime shows: ask at the office.

The Perseids peak around 12 and 13 August, and the Alqueva sky, Starlight certified, is among the best in the peninsula to see them. The Cumeada telescope session runs Tuesday to Saturday and in summer starts after ten: book it in good time.

The Monsaraz river beach has lifeguards and a children's area in swimming season, with the still water of Lake Alqueva. At midday the village scorches: swim in the morning, lunch in the shade and climb to the castle as the sun drops. 15 August is a holiday in Portugal too.

In August the Atlantic at Ericeira cools what the Alentejo heats: fish on the rocks, a surf lesson and jacket nights. 15 August is a holiday in Portugal and the Lisbon coast fills up: book the hotel and the lesson weeks ahead. Mafra palace is closed on Tuesdays.

From May to October the high roads of the Serra da Estrela are open, and in August, at almost two thousand metres, the Torre has the temperature Badajoz lacks. The Covão d'Ametade lagoon, among birches, gives shade for lunch. Two nights in Manteigas.
15 August is La Alberca's main festival, with the Diagosto, and the village fills: if you want the festival, it is your date; if you want calm, go another week. The nights are cool in the sierra and the water in the gorges is welcome at midday.

In summer sunset comes late, and the guided visit to Trujillo castle leaves at 20:00 until 15 August. A three-wine tasting at Bodegas HABLA at midday, with tapas, and back to Badajoz at night: whoever tastes should not drive.
Questions
Yes, the Assunção de Nossa Senhora. The Lisbon coast and Lake Alqueva have more people that day.
In July and August, with night performances in the Roman theatre. The dates and programme are published each spring.
They peak around 12 and 13 August, although they can be seen several nights before and after. Look for a dark sky, like Alqueva's.
In the Serra da Estrela and La Alberca, with cool nights, and in Ericeira, with the Atlantic.
Geocaliahttps://www.geocalia.com/en/spain/extremadura/badajoz/getaways/august-long-weekend