The rain is here far too early – and that could just be the beginning! In Tumbes and Piura, exceptional rainfall occurred at the end of September. Records were broken, the Tumbes River swelled significantly, and the sea off the coast is significantly warmer than usual. Now, all eyes are on October, November, and the summer of 2027.
78.5 LITERS OF RAIN! Tumbes takes a real hit
You don't usually expect this much water here in September! At the Cañaveral measuring station in the Tumbes region, 78.5 millimeters of precipitation were recorded within just 24 hours on September 26th. This corresponds to 78.5 liters of water for every square meter. Cabo Inga also reported exceptionally heavy rainfall with 72 millimeters within a single day.
For the Peruvian weather service Senamhi, this development is striking. According to the authority, the precipitation recorded since September 22nd confirms an unusually early start to the rainy season on the north coast. This is not just a single heavy rain shower, but potentially the beginning of a longer-lasting weather pattern.
PIURA IS ALSO HIT! Talara breaks an old September record
The change in weather is also noticeable in Piura. At the El Alto station in the province of Talara, 13.5 millimeters of rain were measured within a day. While this might seem small compared to the amounts in Tumbes, it is extraordinary for this location.
According to Senamhi, the previous September record was just three millimeters, dating back to 1977. This old peak has now been significantly surpassed. Especially on the normally arid coast of Piura, this demonstrates just how unusual the current weather situation is.
THE TUMBES RIVER SWELLS! Almost 500 cubic meters per second
A lot of that rain eventually ends up in the river – and that is where the development becomes particularly visible. On the morning of September 27th, Senamhi recorded a flow rate of 492.99 cubic meters per second for the Tumbes River at the El Tigre hydrological station.
A significant portion of this water comes from Ecuador. Heavy rainfall had previously fallen in the upper and middle reaches of the binational Puyango–Tumbes basin. But it also rained on the Peruvian side, including in Casitas and San Jacinto. Senamhi is therefore closely monitoring the further development of the river.
THE SEA IS TOO WARM! El Niño heats up Northern Peru
Now comes the deciding factor: El Niño Costero. Off parts of the northern Peruvian coast, the sea surface temperature is currently well above typical values. Deviations of four to five degrees have been reported in some areas.
This has consequences. Warmer seawater means stronger evaporation and therefore more moisture in the atmosphere. When these moist air masses meet the right weather conditions, heavy rain clouds can develop. According to Senamhi, this exact combination is contributing to the current rainfall in Tumbes and Piura. The fact that El Niño is already clearly being felt in the region was already apparent: PeruMagazin reported on the extraordinary winter heat in Piura and the influence of El Niño.
AND NOW? The next few days remain unsettled
After the unusually wet September, a continuous rainy period is not expected just yet. However, that by no means suggests that the danger has passed. It is more likely that there will be an alternation between dry, warm spells and new rain episodes, which can also be heavier in some places.
Tumbes, Piura, and the middle and higher elevations in the north must be monitored closely. Precipitation there can also influence the water levels of the rivers on the coast with a time delay. Therefore, what matters is not only how much rain falls directly in the cities, but also what happens further inland and in neighboring Ecuador.
OCTOBER WILL BE EXCITING! The rain could return more frequently
The next important phase begins in October. Senamhi expects increasing precipitation activity on the north coast over the coming months. This could mean that rain episodes in Tumbes and Piura occur more frequently. This explicitly does not mean that it will now rain every day for weeks.
The bigger problem is individual heavy precipitation events. In Northern Peru, just a few hours of heavy rain can be enough to flood streets, activate dry ravines (*quebradas*), or cause smaller watercourses to swell rapidly. Sullana, Talara, and the inland areas of Piura must therefore also be watched carefully.
FROM NOVEMBER IT GETS SERIOUS! Risk increases significantly
November could become a particularly important phase. The weather pattern will then shift increasingly toward the actual rainy season. At the same time, the unusually high sea temperatures off the coast remain a major uncertainty factor.
Senamhi expects increasing rain activity on the north coast starting in November. The rivers in the northern Pacific region could also carry more water than usual. For Tumbes and Piura, this increases the risk that individual rain events will escalate into larger local problems.
SUMMER 2027! The worst could be yet to come
Looking only at the coming weeks is therefore not enough. The current El Niño Costero situation is much more extensive. Between October and December, Senamhi expects increasingly frequent and intense rainfall in coastal regions that have historically been affected by El Niño events.
The period with the greatest potential for impacts from river overflows, activated ravines, and flooding is expected between December and part of the summer of 2027. Consequently, what Tumbes and Piura experienced at the end of September might have been less of a climax and more of a very early warning signal.
IS SEVERE FLOODING IMMINENT?
It is currently impossible to make a reliable prediction. An unusually wet September and a warm Pacific do not automatically mean that the devastating floods of previous El Niño events will be repeated.
That is precisely why the next few weeks must be monitored closely. The development of sea temperatures, the frequency of stronger rain systems, and river levels will be decisive. Areas where rivers can burst their banks or where dry ravines suddenly carry large volumes of water during heavy rain are particularly at risk.
NORTHERN PERU MUST PREPARE!
For Tumbes and Piura, the crucial message is therefore not panic, but preparation. Watch the situation in October, become especially vigilant from November onwards, and take the summer of 2027 seriously starting now.
No one can reliably predict today exactly how much rain will fall in a specific location in several weeks' time. However, the overall trend is clear: Northern Peru must brace itself for more rain in the coming months.
PeruMagazin will continue to monitor developments in Tumbes, Piura, and Northern Peru and report on new warnings from Senamhi, rising river levels, and the further evolution of El Niño Costero.
Events in Northern Peru
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Sources: Servicio Nacional de Meteorología e Hidrología del Perú (Senamhi), September 2026 · Agencia Andina, 09/21–09/28/2026 · El Peruano, 09/28/2026. Image source: Agencia Andina / Difusión, photograph from Tumbes, 09/25/2026.
