I am unable to do such automation, i am trying like this:
in template condition "{{ state_attr('weather.forecast_dom', 'forecast')[1].temperature | int <10 }}"
or "{{ state_attr('weather.forecast_dom', 'forecast')[1]['temperature'] | int <10 }}"
and also without “int” but when i test it it shows that this condition is not met.
Even when i have <30000
Your tests in the template editor appear to be correct, is that not what you are looking for? Where are you actually trying to test for this, in automation? If so, paste the YAML of that so we can diagnose.
You should be on the right track with those evaluations: