A massive power outage struck significant portions of Portugal and Spain at 10:34 UTC on April 28, grinding transportation to a halt, shutting retail businesses, and otherwise disrupting everyday activities and services. Parts of France were also reportedly impacted by the power outage. Portugal’s electrical grid operator blamed the outage on a “fault in the Spanish electricity grid”, and later stated that “due to extreme temperature variations in the interior of Spain, there were anomalous oscillations in the very high voltage lines (400 kilovolts), a phenomenon known as ‘induced atmospheric vibration’” and that “These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network.”
The breadth of Cloudflare’s network and our customer base provides us with a unique perspective on Internet resilience, enabling us to observe the Internet impact of this power outage at both a local and national level, as well as at a network level, across traffic, network quality, and routing metrics.
In Portugal, Internet traffic dropped as the power grid failed, with traffic immediately dropping by half as compared to the previous week, falling to approximately 90% below the previous week within the next five hours.
Request traffic from users in Portugal to Cloudflare’s 1.1.1.1 DNS resolver also fell when the power went out, initially dropping by 40% as compared to the previous week, and falling further over the next several hours.
At a network level, the loss of Internet traffic from local providers including NOS, Vodafone, MEO, and NOWO was swift and significant. The Cloudflare Radar graphs below show that traffic from those networks effectively evaporated over the hours after the power outage began. The autonomous systems (ASNs) shown below for these providers may carry a mix of fixed and mobile broadband traffic. However, MEO breaks out at least some of their mobile traffic onto a separate ASN, and the graph below for MEO-MOVEL (AS42863) shows that request traffic from that network more than doubled after the power went out, as subscribers turned to their mobile devices for information about what was happening. However, despite the initial spike, this mobile traffic also fell over the next several hours, dropping to approximately half of the volume seen the prior week.
In addition to looking at traffic at a national and network level, we can also look at traffic at a regional level. As noted above, the power outage did not impact every region of the country. The traffic graphs below show the changes in Internet traffic from the parts of Portugal where an impact was observed.
In Lisbon and Porto, a sharp, but limited drop in traffic was observed as the power outage began, with traffic recovering slightly almost as quickly. However, traffic gradually declined in the subsequent hours, in contrast to the other regions reviewed below.
The most significant immediate traffic drops were observed in Aveiro, Beja, Bragança, Castelo Branco, Évora, Faro, Guarda, Portalegre, Santarém, Viana do Castelo, Vila Real, and Viseu. In these areas, traffic fell and then quickly stabilized at very low volumes. In Braga and Setúbal, traffic declined more gradually after the initial drop.
The power outage also impacted the quality of connectivity at a national level in Portugal. Prior to the loss of power, median download speeds across the country were around 40 Mbps, but within several hours after the state of the outage, fell as low as 15 Mbps. As expected, latency at a country level saw an opposite impact. Prior to the loss of power, median latency was around 20 ms. However, it gradually grew to as much as 50 ms. The lower download speeds and higher latency are likely due to the congestion of the network links that remained available.
Network infrastructure in Portugal was also impacted by the power outage, with the impact seen as a drop in announced IP address space. (This means that portions of Portuguese providers’ networks are no longer visible to the rest of the Internet.) The number of announced IPv4 /24s (blocks of 256 IPv4 addresses) dropped by ~300 (around 1.2%), and the number of announced IPv6 /48s (blocks of over 1.2 octillion IPv6 addresses) dropped from 17,928,551 to 16,355,607 (around 9%). Address space began to drop further after 16:00 UTC, possibly as a result of backup power being exhausted and associated network infrastructure falling offline.
In Spain, Internet traffic dropped as the power grid failed, with traffic immediately dropping by around 60% as compared to the previous week, falling to approximately 80% below the previous week within the next five hours.
Request traffic from users in Spain to Cloudflare’s 1.1.1.1 DNS resolver also fell when the power went out, initially dropping by 54% as compared to the previous week, but quickly stabilizing.
At a network level, traffic volumes from the top five ASNs in Spain fell rapidly once power was lost, with most declining gradually over the next several hours. In contrast, traffic from Digi Spain Telecom (AS57269) fell quickly, but then stabilized at the lower level. In comparison to the previous week, traffic from these providers fell between 75% and 93% in the hours after the power outage began.
In most of the impacted regions in Spain, traffic dropped off quickly and stabilized, or continued to fall further. However, some recovery in traffic is also evident, and can be seen in Navarre, La Rioja, Cantabria, and Basque Country. This traffic recovery is likely associated with an initial restoration of power in those regions, as an update from Red Eléctrica (operator of Spain’s national electricity grid) noted that “Electricity is now available in parts of Catalonia, Aragon, the Basque Country, Galicia, Asturias, Navarre, Castile and León, Extremadura, Andalusia, and La Rioja.”
The power outage also impacted the quality of connectivity at a national level in Spain. Prior to the loss of power, median download speeds across the country were around 35 Mbps, but within several hours after the state of the outage, fell as low as 19 Mbps. Interestingly, the median bandwidth didn’t see the clean gradual decline as it did in Portugal, instead falling and recovering twice before gradually declining.
As expected, latency at a country level saw a significant increase. Prior to the loss of power, median latency was around 22 ms, but grew to as much as 40 ms. As in Portugal, the lower download speeds and higher latency are likely due to the congestion of the network links that remained available.
Similar to Portugal, network infrastructure in Spain was also impacted by the power outage, with the impact seen as a drop in announced IP address space. By 14:30 UTC, the number of announced IPv4 /24 address blocks had fallen by around 2.4%, and continued to drop further over the following hours. The number of announced IPv6 /48 address blocks fell by over 8% during that same time span, and also continued to drop in the following hours.
Impacts in other European countries
Parts of Andorra and France were also reportedly impacted by the power outage, with additional outages reported as far away as Belgium. At a national level, no traffic disruptions were evident in any of the countries.
Analysis of traffic at a regional level in France shows a slight decline concurrent with the power outage in several regions, but the drops were nominal in comparison to Spain and Portugal, and traffic volumes recovered to expected levels within 90 minutes. No impact was evident at a regional level in Andorra.
It appears that Morocco may have been impacted in some fashion by the power outage, or at least Orange Maroc was. In a post on X, the provider stated (translated) “Internet traffic has been disrupted following a massive power outage in Spain and Portugal, which is affecting international connections.” Cloudflare Radar shows that traffic from the network fell sharply around 12:00 UTC, 90 minutes after the power outage began, with a full outage beginning around 15:00 UTC.
Power restoration in Spain had already started as this post was being written, and full recovery will likely take hours to days. As power is restored, Internet traffic and other metrics will recover as well. The current state of Internet connectivity in Spain and Portugal can be tracked on Cloudflare Radar.
The Cloudflare Radar team is constantly monitoring for Internet disruptions, sharing our observations on the Cloudflare Radar Outage Center, via social media, and in posts on blog.cloudflare.com. Follow us on social media at @CloudflareRadar (X), noc.social/@cloudflareradar (Mastodon), and radar.cloudflare.com (Bluesky), or contact us via email.