Many people seem to agree with the forecast by @geoffodlum claiming that the US or Israel wouldn't want to take the risk of attacking a facility in Iran. I agree with the sentiment on the US, but for Israel, less so. This is because of Israel's strikes in Syria today, the deadliest in months. (Reuters) Netanyahu's regime doesn't seem to be afraid of causing turmoil in the region.
The base rate for an attack happening in a month seems to be 4.8% (an updated version of @johnnycaffeine 's base rate: 8 attacks / 165 months). The base rate for an attack happening in the next months is 1-0.952^6 ≈ 25%.
This is much higher than the crowd. I don't personally have a good inside view on this, and I can imagine some considerations for a bigger/smaller probability, but I'm hesitant to bet on them. However, I'll adjust my forecast based on the crowd forecast, and will choose the middle between the crowd (5%) and my forecast, resulting in 15%.
Su-35 crashed in Crimea yesterday (Reuters). If such incidents happen often, it reduces the likelihood of Russia wanting to sell them to Iran. Apparently Russia has indeed lost many Su-35s lately, as pointed by @cmeinel .
I'll start with a probability of slightly lower than the Pro Forecasters for both of the weapons systems.