The Panama Canal Just Crossed From Cargo Limits to Traffic Limits

Advisory to Shipping A-29-2026, signed by Vice President for Operations Boris Moreno Vásquez and dated 20 August 2026, reduces the number of daily booking slots at the Panama Canal. For booking dates beginning 4 September the total falls to 34, split as nine at the Neopanamax locks and 25 at the Panamax locks. For booking dates beginning 15 September the Panamax figure falls again to 23, bringing the daily total to 32.

That is the threshold. It was written down here on 22 July, before it happened, with the observable named and the source of resolution specified.

What the July Article Said Would Count

The value of a threshold is that it is set in advance and can be wrong. Here is the one this site published on 22 July, in Panama Cuts the Draft, Not the Traffic, unedited:

Two arms, either of which would count. Both have now been crossed, fifteen days apart, though not in the same way, and the order they arrived in is the interesting part.

Both Arms, Fifteen Days Apart

On 5 August the Authority announced its fourth and fifth draft adjustments: a reduction to 48.0 feet (14.63 metres) effective 26 August, and to 47.5 feet (14.48 metres) effective 3 September. A lower maximum draft is a stricter limit, so both are steps beyond the 48.5-foot level scheduled for 15 August. The second threshold was crossed in the announced schedule on 5 August, although those deeper restrictions were later postponed before taking effect. The Authority was also explicit about what it was not doing. Its announcement stated that the draft adjustment "will not affect the number of daily vessel transits."

Fifteen days later it announced a reduction in daily booking slots for September transit dates.

And in the same advisory, it moved the draft steps the other way. Based on the current level of Gatun Lake and the latest weather projections, the 48.0-foot restriction slips from 26 August to 2 September, and the 47.5-foot restriction slips from 3 September to 1 October. Neither is cancelled. The first slips by one week, the second by four. So of the two thresholds, only the slot reduction has been formally adopted, with the affected transit dates beginning in September. The draft steps that crossed the other one are back on the calendar, unimplemented.

The Same Lever, Not the Same Severity

One qualification belongs here immediately, because "2023-24 territory" is easy to over-read. The canal has entered the same category of intervention used during 2023-24. It has not entered the same degree of disruption.

In that episode the Authority cut daily booking slots to 24 beginning 7 November 2023. It went further from there, down to 22 slots in December 2023, and announced a reduction to 18 for February 2024 booking dates, which was withdrawn before implementation when rainfall returned. That sequence is what produced the queues, the auction premiums and the rerouting via Suez and the Cape of Good Hope that most readers remember.

The new 32-slot limit remains ten slots above December 2023's 22-slot limit. What has changed this month is the kind of measure being used, from limiting cargo per ship to limiting bookable ships. Nothing here should be read as saying the degree is comparable, because it is not.

Why Both Directions at Once

This reads as a contradiction only if draft and booking capacity are treated as two settings on the same dial. They are not, and the July article made the same distinction from the other side.

Draft is governed by the level of Gatun Lake. If the lake surface is high enough, a deeply loaded ship clears the channel, and the Authority has no water-related reason to make it load lighter. The number of lockages is governed by the volume the lake can afford to spend, because lockages consume stored fresh water, although cross-filling and water-saving basins recover or reuse some of it. A lake can be high today and still be on course to run short in April.

The most plausible reading is that current lake depth allows the Authority to postpone the deeper draft cuts, while the accumulated rainfall and inflow deficits justify conserving the reservoir by reducing future lockages. On that reading A-29-2026 is coherent rather than contradictory, and the Authority has not softened its position so much as switched to the lever that saves water.

That is this site's interpretation. The Authority does not explain this particular combination of measures in those words. What the advisory does say plainly is that they exist to "preserve service reliability, safeguard water resources for human consumption, and provide customers with timely and transparent information."

The Hydrology Behind It

The advisory gives two observed figures for the current hydrological year, May through August, both for the Canal watershed and both against the historical average for the same period:

• Cumulative rainfall: 34% below average.
• Watershed inflows: 44% below average.

The gap between those two numbers is worth pausing on. Inflows are running further below normal than rainfall is, which the advisory describes as "a substantially reduced hydrologic response despite the onset of the rainy season." The advisory does not attribute that gap to one mechanism. Antecedent soil moisture, rainfall distribution and intensity, evapotranspiration, and watershed storage can all affect how rainfall becomes inflow. What the two figures establish together is that the reservoir has received proportionally less than the rain gauge alone would suggest.

Those two figures are observations. The rest of the Authority's case is forecast: it cites the possibility that "the anticipated severity of the 2026-2027 El Niño event could further reduce precipitation and runoff during the remainder of the wet season," and concerns about "water availability during the upcoming 2027 dry season (January to April)." Observed deficit plus forecast deficit is the combination it names, and it is worth keeping the two apart when reading it.

Three Months Ago, None of This Was Forecast

On 18 May the Authority published a statement titled "The Panama Canal Responds to the Risk of El Niño with Foresight and Maintains Operational Stability." It said the canal was "maintaining 38 daily transits" and added a flat forward-looking claim: "Current data does not forecast the need for transit restrictions through December 31, 2026."

Three months later it is restricting bookable capacity for transit dates from early September.

One caution on arithmetic. The May statement counts "daily transits" and the August advisory counts daily slots in the booking system. Those are not certainly the same unit, since a transit and a bookable reservation are different things, so this article does not compute a percentage cut from 38 to 34. The direction is unambiguous and the reversal of the December claim is unambiguous. The exact magnitude is not, and would need the Authority to state both figures on the same basis.

Where the Event Actually Stands

The Authority is not guessing about the forecast half of its case. NOAA's Climate Prediction Center, in its 13 August 2026 diagnostic discussion, holds an El Niño Advisory and puts the chance of a very strong event during Northern Hemisphere fall and winter 2026-27 at greater than 90%. For October through December it gives a 69% chance of a value at or above +2.5 C on the three-month Relative Oceanic Niño Index, which would exceed every event back to 1950.

Here is where the current event sits against the same season in four predecessors, using RONI, NOAA's relative index, which subtracts the tropical-mean anomaly before comparing:

The 2023 line is the one worth noting. The event that preceded the 2023-24 canal restrictions was, at this point in its calendar, a +0.28 season. The present one is at +0.98, seven tenths of a degree warmer at the equivalent point, and CPC expects it to keep strengthening.

That comparison establishes one thing and no more: the developing Pacific event is further advanced now than it was at the same calendar point in 2023. It does not explain why watershed conditions differ between the two years, and it does not establish that Panama will experience a worse drought. Rainfall over the Canal watershed is a regional outcome with its own drivers, and a warmer index does not translate into a fixed quantity of missing rain over Gatun. The Authority's decision rests on observed rainfall, observed inflows, lake management and its own forecasts. It does not rest on an index comparison, and neither should any conclusion drawn from this table.

These are relative index values from NOAA's RONI series, three-month running means, retrieved 21 August 2026. They are not interchangeable with conventional Niño 3.4 anomalies. Compared like for like on the same three-month season, MJJ 2026 is +0.98 C on RONI and +1.39 C on the ONI, a difference of about 0.41 C. That offset is specific to this season and to these two seasonal products. It is not a fixed conversion, and it does not carry over to the weekly tables, which are a different product with a different offset. Mixing any of these is the single most common error in coverage of this event.

A Detail Almost Nobody Will Report

Alongside the slot reduction, the Authority is restructuring how the daily auction slot is allocated. From 3 September, auction slots for Neopanamax, Super and Regular vessels are organised into four groups by cargo type: LNG and LPG; dry bulk, general cargo and others; container, vehicle carriers and refrigerated; chemical and crude or product tankers. Customers already holding a slot for the same transit date through other channels become ineligible for an additional one unless no other bidder exists, and in the Neopanamax locks the highest-TEU container vessels get allocation priority.

That is an allocation design, not just a smaller number. The Authority frames it as promoting "a more equitable allocation process that better reflects market composition, including various cargo types and market segment characteristics," and as maximising water-use efficiency. Whatever the motivation, the practical effect is that with fewer slots on offer, the rules for distributing them among cargo types become worth reading closely.

What This Is Not

• Not a closure. The canal is operating. Bookable capacity is being reduced.
• Not a queue, yet. The restrictions begin with September booking dates. No large accumulation of waiting ships has been reported, and this article does not claim one. The Authority's own press statement warns only that a reduction in daily transits "may increase waiting times for vessels arriving at the waterway without a secured reservation." That warning is prospective and appears in the press release rather than the signed advisory.
• Not a pure El Niño attribution. The Authority names three things together: observed watershed deficits, a forecast of worsening conditions, and a deliberate policy of conserving water for 2027 and for human consumption. More than half of Panama's population draws its water from the same system. El Niño is one input into a decision that has other inputs.
• Not yet a disruption to global supply chains. That would require queues, rerouting or surcharges, and those are things to look for rather than things to report.

What to Watch

• Whether the 48.0-foot draft step actually takes effect on 2 September, or slips a second time.
• Whether total daily slots go below 32 after 15 September, which would be a third reduction inside two months.
• Gatun Lake levels through the remainder of the wet season, published by the Authority, which normally recharges the reservoir before the dry season begins around January.
• Auction premiums under the new four-group structure, an early and public measure of how tight the reduced allocation proves to be.
• Whether carriers begin publishing low-water or canal surcharges, the first sign that costs are being passed along.

The July piece said the real stress test arrives after the event peaks, in the January-to-April dry season. Nothing in the 20 August advisory changes that. What changed is that the Authority is no longer treating the wet season as a period it can simply get through. It is treating it as the last chance to store water, and it has started paying for that storage in booking capacity.