Following the Israel Security Council's majority vote authorizing Iranian "action" when required, we are wondering at this stage the "when" and not the "if". Rapidan and other strategic analysts are crunching data on a possible date for the attack considering carrier deployment and moonless nights.
From Rapidan Group
And here is the latest naval update from Stratfor. Keep your eye on CVN 65.Timing Considerations
Based on press reports, officials see high odds of an attack sometime between 2Q12 and the end of the year, with most pointing to 2Q or 3Q.
If Israel elects to conduct a conventional military strike, the optimal conditions would be moonless and cloudless nights. “Operation Orchard,” Israel’s attack on Syria’s reactor at Al-Kibar on Sep 6, 2007, took place 5 days before the new moon. This suggests windows starting about 5 days before a new moon and ending five days after - see the table below. Low humidity is also ideal, but not required.
Attackers would want to avoid sandstorms, which have afflicted Iran in April, July, and September in recent years. Last year, a large sandstorm in mid-April hit 20 provinces, forcing the shutdown of schools and businesses. Sandstorms are visible and predictable, however, and would be taken into account by planners.
For non-kinetic options, climate is not a consideration to our knowledge. Presumably, they would be tried before kinetic ones and only after leaders were convinced Iran had not yet felt enough pain to compel it to freeze enrichment.