(1) 今日は、寒いです （今日は、寒い）。
(2) 今日は、寒いですね （今日は、寒いね）。
It doesn't change the whole meaning of the sentence, but it change how it sounds. In this case, the sentence with ね sounds much more friendly. ね brings us closer together!
Oh, I forgot to say that ね can be used by itself!!
/kyou no tesuto muzukashikatta ne/
Today's test was hard, wasn't it?
/nee. san-ban no kotae nani ni natta?/
Yeah. What was the answer to question no.3?
It's used mainly among women. Maybe because women have better empathy than men? I guess so. In another case, ね is used by itself to ask for someone's agreement. Here's an example. 3 girls are talking.
/watashi saikin futochatte/
I got fat recently..
/eh... sonna koto naiyo. ne?/
Well.. I don't think so, do you?
Um.. me neither!
I often hear girls say "I'm fat" even if she's in a good shape. And the other girls 99% reply "no, you aren't." But no matter how fat actually she is, the other girl would say "no, you aren't". Right? ね?
Anyway, let's see other sentence ending particles.
In contrast to the function of ね, よ indicates that the information (今日は寒い) is new to the listener. Or, you want to give advice to him.
/shoujiki ni itta houga ii/
It'd be better to say honestly.
/shoujiki ni itta houga ii yo/
You should say honestly.
It also makes the sentence sound soft.
By the way, have you heard "ダメよ～ダメダメ" which is selected as one of the top buzzwords this year in Japan? This ダメよ consists of ダメ /dame/ (not good) + よ. "That's no-no", in English.
(4) 今日は、寒いですか。 Is it cold today?
I guess I don't have to explain this sentence ending particle.
I've said several times before, です is just attached to the sentence so as to make it polite. So we usually speak without it when we talk with friends or family members.
sounds a bit strange to me. It's not wrong, but it sounds a little bluntly. Or, it might indicate that the speaker disagree about the idea (今日は寒い). Do you think it's cold today? (Though I don't think so)
And in this case, he speaks to himself.
/sokka, ashita wa ame ka/
Oh I see. It will rain tomorrow.
Then, how do we say "is it cold?" in casual term? Well, we'd simply ask, 寒い？
By the way, in my regional dialect, people say 寒いけ？ instead of 寒い？XD
That's all for today! Try using some sentence ending particles when you talk to your Japanese friend! Your Japanese certainly sounds more fluent! ：D
Thank you for reading -★