Re: i heard that the sex of crocodile is determined by weather.

Absolutely!

Crocodiles (and some sea turtles) have "temperature dependent sex 
determination".

This means the fertilized egg which is laid in the nest has an unknown 
sex. The temperature the egg is kept at has a strong impact on the 
development of the embryo.

To produce a male, temperatures generally need to be around 31/32 degrees 
Celcius, with females being produced at slightly lower temperatures. 
Usually, males are born from the top of the nest, where it is warmer than 
the very bottom of the nest.

Of course, temperatures either side of these cause the embryo to die 
within the egg.

This has massive implications with respect to global warming and 
threatened species management. If the climate changes by a few degrees, 
only one sex may be produced, with catastrophic effects on population 
numbers.

Hope this clarifies the issue a little!

cheers,

Alastair