Political pressure brought all sides to Baghdad. Ecological pressure kept them there.
The six world powers had planned to hold a single day of talks with Iran. But Baghdad's sandstorms closed the city's airport.
So negotiators were forced to spend an entire second day sequestered in the grounds of Baghdad's fortified former Green Zone.
Thanks to the weather then, this round of talks turned into the most extensive negotiations between the P5+1 and Iran for more than two years.
During the talks there were occasional reminders of the Iraqi capital's continuing unrest.
Shortly after midday on the second day, a loud explosion was heard in the distance. The police later confirmed that this was a mortar attack on the other side of the river. One person was killed in the explosion.
For Iran's chief negotiator Saeed Jalili, the strike in the distance may have provoked a few memories of Iraqi explosions. He lost his lower right leg while fighting in the Iran-Iraq war of the 1980s (he now walks with a noticeable limp).
The negotiations were held in this city at the request of Mr Jalili and his delegation.
No-one expected any final agreements to come out of this particular round. That may be just as well, because it looks like the negotiators didn't come anywhere near to getting one.
Two days of intensive negotiations appear to demonstrate Iran and the world powers remain far apart on the most significant issue dividing them: uranium enrichment.
Several UN Security Council resolutions have called on Iran to halt all uranium enrichment while concern remains over the country's activities and intentions.
But Tehran has continued to process low-enriched uranium. And in February 2010 it began processing medium-enriched uranium - a procedure also known as 20% enrichment.
It's the processing of medium-enriched uranium that so concerns the West.
20% enrichment does have civilian uses. But it's also a technically significant step towards the potential production of weapons-grade uranium.
But Iran insists that it has no intention of stopping any of its enrichment work. It says its processing is not designed for weapons.
"Enrichment for peaceful purposes is one of the irrefutable rights of the Islamic Republic of Iran," Mr Jalili said during his closing remarks in Baghdad. This was a point that he repeated several times.
Iran's tactic appears to be to hold out for an acceptance by the P5+1 of its right to enrich.
But at these talks, it would appear that the world powers maintained their position that all enrichment work must stop. The gulf remains.
Both sides agreed to continue talking over the next few weeks. Contacts may be led by the chief negotiators' respective deputies: Helga Schmid for the P5+1 and Ali Bagheri for Iran.
The talks will run in parallel with the recent activities of the International Atomic Energy Agency (IAEA).
Earlier this week, the agency's head, Yukiya Amano, travelled to Tehran in order to persuade the Iranian government to allow better access for his inspectors.
He appears to have won agreement for more inspections. Progress between Iran and the IAEA will be closely monitored by the nuclear negotiators.
As fits the rather curious custom of this series of nuclear talks, diplomats picked a new venue for the next round - Moscow.
Discussion over venues appears to take up a disproportionate amount of negotiating time.
Western diplomats suggest privately that they would rather pick a single venue such as Geneva and stick with it.
But Iran suggests that it feels more comfortable negotiating in non-Western cities - ideally in countries which do not support sanctions against Tehran.
Iran's preference for alternative venues has turned the nuclear negotiating process into an unusual world tour.
Russia takes part in this series of talks on the side of the world powers - but it has also expressed its public concern about unilateral Western measures against Iran.
This would appear to make it a suitable compromise host for the next set of talks. At least the sand won't be a problem in Moscow.