Help with the grammar だと and なるみたい


So, I was reading a manga, and this sentence came up:

> 今日予報だと暑くなるみたいだよ。

I translated it as:

> It looks like it's going to become hot with today's forecast.

There are a few questions I'd like to ask: What's だと、in this sentence?  
First I thought it meant `according to,` but when I searched around they said,
`if or when.`  
Like, `If you have today's forecast, it's going to be hot.` But does that mean
something like, `If you're looking at today's forecast, it's going to be hot,`
or something completely different?

Did I translate the `it's going to be hot` well?




だと might not specifically represent the idea of "according to", but I think
"According to the forecast, it's going to get hot today (apparently)." would
be an acceptable translation.

possible duplicate of [What does the だと mean in
日本だと?](https://japanese.stackexchange.com/questions/3574/what-does-
the-%E3%81%A0%E3%81%A8-mean-in-%E6%97%A5%E6%9C%AC%E3%81%A0%E3%81%A8)

