A very hot day

[There is two ways you can say this Entry. It depends on if you are talking past tense or present tense when writing it and conveying it to others. I will do both and you can figure it out which one you like and which one sounds good to you.]

Original Text: 

Today is too hot that makes me very irritable.The original plan is to see a movie with my boy friend,but he has other thing to do.So the plan is canceled.How I wish he could accompany me.He promises me he would accompany me as long as he has time.I believe him!

Present Tense:

Today is way too hot,  that makes me feel very irritable. The original plan is to see a movie with my boyfriend but he has other things to do. So the plan has been canceled. I wish he could accompany me. He promised me he would accompany me as long as he has time. I believe him!

Past Tense:

Today was too hot, that made me very irritable.The original plan was to see a movie with my boyfriend but he has other things to do. So our plans were canceled. I wish he could accompany me. He promised me he would accompany me as long as he has time. I believe him!

Remeber to space between sentences. In writing English that is important (at least in the United States). It tells you when your thought was complete like a period (.) or a exclamation point (!) or even a question mark (?).

A very hot day

Today is [was or has been] too hot that makes me very irritable  [this part doesn't sound good... you can say and this makes me feel irritated] .The original plan is [was] to see a movie with my boyfriend,but he has other thing to do.So the plan is cancelled.How I wish he could accompany me.He promises [promised] me he would accompany me as long as he has time.I believe him!

mistakes highlighted in red.

correction next to it.