C++ : compile time assert the value of a floating point number

I am using C++ 11. I have a floating point number.

float some_float = 3.0;

Now I want to compile time check that this number is greater than some value. Say that I want to compile time assert that some_float is greater than 1.0. i am trying this:

static_assert(some_float > 1.0);

But, it errors out complaining,

error: static_assert expression is not an integral constant expression
static_assert(some_float > 1.0);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Question:
what is wrong that I am doing?
How can I assert at compile time that some_float is set to something above 1.0?