Via the New York Times:

8 Are Killed by Bombings in Restive City in South Iran

President Mahmoud Ahmadinejad had been expected to meet his cabinet in the city, but the trip was canceled Monday evening. His office said the four-day trip was canceled because of bad weather, the IRNA news agency reported Monday. The explosions occurred at the time he had been expected to make a speech in Ahwaz.

..his office told the BBC the visit had been cancelled due to bad weather.

Mr Ahmadinejad's media chief said the president had feared the weather would have prevented people from attending his meetings in the city.

Here's a photo taken on the same day of the bombing. The weather doesn't look so bad...no umbrellas, not even a breeze.

More from the Times:

A series of deadly bombs went off in Ahwaz last year, and the government accused Britain of provoking the attacks. Foreign Minister Manouchehr Mottaki said in October that Iran had proof of British involvement.

Britain has repeatedly denied the accusations.

Mostafa Pourmohammadi, the interior minister, said the bombings on Tuesday were motivated by foreigners. Mr. Ahmadinejad ordered the Intelligence and Foreign Ministries to investigate "the role of foreign hands" in the bombings, the ISNA student news agency reported...

.."Iran has always been victimized by terrorism, and these blind blasts show the continuity of brutal acts against Iran by international terrorists," he added....

...Ahwaz is the capital of Khuzestan Province and home to a Sunni Arab minority. The province borders Iraq and was battered during the Iran-Iraq war. It has remained one of the least developed regions in the country since then.

Unrest broke out in the city in April, and several people were killed after rumors spread that the government planned to relocate Arabs.