Sims teen or older can be struck by lightning. Selectable sims struck by lightning have a flat 1% chance of dying. Any sim, selectable or not, will suffer +50 energy (yes that's plus), -100 comfort, -50 hunger, -150 hygiene, -150 bladder, -100 fun. Plantsims suffer -50 sunshine. This could cause secondary death by hunger, drowning or sunlight.

Servos who survive have a 60% chance of running amok, a 20% chance of getting an energy boost of 200, and a 20% chance of no event.

What are the chances of a sim getting hit by lightning? The evolution of storms and lightning is complicated but I'll give a synopsis here.

Rain falls in one of three intensities: light, heavy and torrential. During heavy and torrential rain there is a chance of a lightning storm forming*, although lightning can strike as long as it is raining. Every ten minutes there is a chance of lightning based on intensity and storming:

  • Light - 2%
  • Heavy, Not Storming - 20%
  • Heavy, Storming - 30%
  • Torrential, Not Storming - 40%
  • Torrential, Storming - 60%

Lightning can be either sheet lighting, which is purely cosmetic, or a localized bolt that hits something. The chance of localized lightning rather than sheet lightning is based on rain intensity: Light 0%, Heavy 15% and Torrential 30%. This chance is increased by 2% per tree on the lot up to a 10% total bonus (so more than five trees don't make lightning more likely).

A lightning strike will consist of 1-3 bolts, again based on intensity. Light rain will always be one bolt. Heavy will be 60% one bolt, 35% two bolts and 5% three bolts. Torrential is 40% one bolt, 35% two bolts and 25% three bolts. The second and third bolt can be either localized or sheet.

When a localized bolt hits, the game first checks for lightning rods. The chance of hitting a lightning rod is 50% + 4% per lightning rod, up to 70% total. Note that means a minimum of 54% for one lightning rod and a maximum of 70% for 5+ rods. My Better Lightning Rods mod increases these odds.

If it does not hit a lightning rod then there is a 50% chance of hitting a tree, a 10% of hitting a sim and a 40% of hitting some other object.

If it can't find an appropriate object--say it wants to hit a sim but there are no sims outside--then it simply cycles through each item first trying to hit any lightning rod, and then any tree, any sim and finally any miscellaneous object.

So what are the chances of a sim being hit by lightning? The chance of a localized lightning strike ranges from 0% (light rain) to 24% (torrential rain, 5+ trees), checked every ten minutes. If a teen or older sim is out in the yard when a localized lighting bolt strikes, then the chance of getting hit is:

  • No lightning rods or trees - 80%
  • No trees, 1 lightning rod - 28%
  • No trees, 5+ lightning rods - 18%
  • Trees, no lightning rods - 5%
  • Trees, 1 lightning rod - 5%
  • Trees, 5+ lightning rods - 3%

So because of the lopsided selection criteria, one tree does more to protect your outdoor sims than a million lightning rods.

*Since writing this I have discovered storm formation is broken and the climate controller will never go into storm mode. This bug is addressed by Lightning Storm Fix.