The wheather was very hot these days,the sun was just like a fireball.I stay at home all day long,it's very boring.After it rained a heavy rain in afternoon,ther are a lot of people go out for fun and take a walk,the wheather was cool,and it make us feel very comfortable.
你的原文这麼短是不太可能有70-80字的,所以如果可以加长的话,就可以：
The wheather was very hot these days,the sun was just like a fireball,to seem like it can melt everything,i feel so hot,so I stay at home all day long,it's very boring!I can only watch TV at home,I can't accept this existence!But after it rain cats and dogs in afternoon,ther are a lot of people go out for fun and take a walk,
the wheather was cool,and it make us feel very comfortable.
I went out of my home and get fun too!How happy is it!
译文：这几天的天气很热,太阳就像一个人火球,好像要把所有东西都融掉,我感到非常的热,所以我整天都呆在屋子里,真是闷啊!我只可以看看电视,我真的接受不了这种生活!但是在下午下了一场大雨之后呢《rain cats and dogs解下了很大的雨》,很多人都下街散步和玩,天气很凉爽,这是人很舒服.
我也下街去玩了,真高兴呀!
我是绝对没有用翻译器的!