In Seville, the mosquitoes that matter come out at dusk.

Yes, and in Seville the evening mosquitoes are the ones to plan around. Culex mosquitoes come out at dusk along the Guadalquivir, and in summer they spread West Nile virus, which makes Seville province Spain's main hotspot for the disease. Most cases are in the river towns south of the city, and a summer city trip needs an evening routine.

Spain's West Nile hotspot

Seville province's West Nile numbers swing widely. In 2020, the first big outbreak, the province had 57 local cases, and 38 of them lived in two neighboring river towns, Coria del Río and La Puebla del Río, according to a 2021 Eurosurveillance study. In 2024, Spain's record year, the Ministry of Health counted 158 cases and 20 deaths nationwide, and the European Centre for Disease Prevention and Control (ECDC) placed 92 of them in Seville province. The ministry pointed to a mild winter, spring rains, a very large rice acreage and a hot summer. In 2025 the province had just 2.

In 2026 ECDC counted 65 locally acquired cases in the province as of October 21, out of 145 in Spain. Press reports of regional figures in August placed cases in several river towns and in Seville city itself. Part of the rise reflects Andalusia's newer testing of mild cases in high-risk zones. Most infections are mild or cause no symptoms, severe illness falls mainly on older adults, and there is no vaccine.

City evenings, river-town nights

Two mosquitoes do most of the biting, both from dusk into the night. The house mosquito, Culex pipiens, breeds in drains, ditches and canals in and around towns. Culex perexiguus breeds in rice fields and watercourses and in outbreak years swarms into the river towns. In 2020 one village-edge trap in the rice country near Coria and La Puebla caught 1,312 in a night, against 12 in 2013.

In the city, the riverbanks, Parque de María Luisa and the Jardines de Murillo have a reputation among forum posters for mosquitoes at sunset, and unscreened rooms or doors onto patios let them in at night. With August afternoons averaging about 82–86°F (28–30°C) and highs near 104°F (40°C), dinner and the evening stroll fall right in the biting hours.

June is the easy month

In 2026 the province's cases rose from mid-July, peaked in late July and early August and tailed off through September, according to the Ministry of Health. June is the lowest-risk summer month, and late July to mid-September is the peak. Spring and fall are quieter. Adult mosquitoes stay active into late autumn, though, and Andalusia even had a March case in 2024.

Where you're going

How the city and the country around it compare for a June–September trip.

Driving on to Portugal? Our Algarve briefing covers the coast west of the border, and the Spain briefing covers Barcelona and the islands.

What travelers report

Paraphrased from a TripAdvisor thread and a 2025 hotel review and linked so you can read them in full. Seville's West Nile seasons swing a lot from year to year, and so do the bites.

• Halo Boutique Hotel, Seville old town · May · 2025

  A guest said the main problem was a mosquito infestation: their ground-floor room next to the hotel's entry door was swarmed, the only alternative offered was the other room off the lobby, and the hotel refused a refund for the unused nights. TripAdvisor ↗

• Seville · summer

  In a thread about two years old, a traveler asked about mosquitoes and West Nile. Replies noted the high number of West Nile cases in Seville province that summer and local protests in Coria del Rio and Isla Mayor; one poster thought the risk to visitors was exaggerated. TripAdvisor ↗

One rule outlasts the trip. Any fever during or after your trip means a doctor visit, and you tell the doctor you were in Seville province. A fever with headache, stiff neck, confusion or weakness within two weeks of a summer trip needs prompt care.

Traveler questions