As Tropical Storm Harvey continues to dump water on Texas and Louisiana, you may be wondering what kind of insurance can provide financial rescue in these situations — and how far ahead you need to buy it.

Insurance for hurricane damage can involve more than one insurance policy. Waiting periods often make it tough to buy certain coverage as a storm is approaching. Other policies are more flexible and could be available depending on how close the storm is.

Here’s a snapshot of the roadblocks you could encounter when trying to buy coverage before a hurricane:

Flood insurance

Home insurance doesn’t cover flooding. You’ll need to buy a separate flood insurance policy, which takes 30 days to take effect, according to

If a hurricane strikes within that 30-day window, your policy won’t pay for flood damage to your home or belongings.

Windstorm insurance

Many homeowners policies include coverage for wind, especially if you don’t live in a hurricane-prone coastal state, so you might not need to buy additional insurance.

But in coastal states like Texas and Florida you’re more likely to need separate wind insurance. See NerdWallet’s guide to hurricane insurance for a list of where to buy windstorm coverage in these areas.