僕も札幌に一年半ほど住んでいましたが、退職後まで暖かい国に行くのを待ちきれなかったです。
質問者様のお求めの英語は「After retirement I would like to live abroad in a warm country」になります。
さらに、札幌の理由を紐づけるなら「After retirement I would like to live abroad in a warm country because right now I live in Sapporo, which is freezing」が良いかと思います。
When I retire, I would love to live somewhere warm.
I would love to retire in a place where the weather is warm year-round.
Since I live in Sapporo where the winters are always cold, I would love to retire somewhere that has warm weather year-round.
"Year-round" is used to express something happening or continuing throughout the entire year, not just for one period or season.
"I would love" is used to express a strong desire of yours.
"Year-round"は、ある期間だけ、あるシーズンだけでなく、一年中あることが起きている、続いているという意味です。
"I would love"は、強い願望を表すフレーズです。
After I retire I want to live in a warmer country.
After I retire I want to emigrate to live somewhere with a warmer climate.
When I retire I will emigrate.
After I retire from work I want to live in a country that has a warmer climate, somewhere with milder winters.
I will emigrate to live in a country that is warmer than here.
When we move to live in another country we call it emigrating or immigration.
I migrated from the UK to live in France which has a warmer climate.
After I retire from work I want to live in a country that has a warmer climate, somewhere with milder winters.
（退職したら、暖かい国に住みたい、冬が寒くない所に）
I will emigrate to live in a country that is warmer than here.（ここよりも暖かい国に移住したい）
「移住」は英語で "emigrating" または "immigration" といいます。
I migrated from the UK to live in France which has a warmer climate.（イギリスからより暖かいフランスに移住しました）
When I retire, I would like to move abroad to a place where it is always warm
After I retire, I want to live abroad - preferably somewhere warm.
I want to move to a warmer climate when I retire.
When you want to explain that you would like to move to a warmer place abroad after you retire; then you may explain this in the following ways:
-When I retire, I would like to move abroad to a place where it is always warm
-After I retire, I want to live abroad - preferably somewhere warm.
-I want to move to a warmer climate when I retire.
「退職後は海外の暖かい国で暮らしたい」は次のように言えます。
-When I retire, I would like to move abroad to a place where it is always warm（退職したら、海外の暖かい国に移住したい）
-After I retire, I want to live abroad - preferably somewhere warm.（退職したら、海外の、できれば暖かい国に移住したい）
-I want to move to a warmer climate when I retire.（退職したら、暖かい所に移住したい）
After I retire, I would like to move somewhere warm.
I am planning to move to a warm country after retirement.
I have had enough of the cold, so I am planning to retire somewhere warm.
I have had enough- finished with, had your fill of.
Planning - what you are intending to do.
After retirement- when you have retired.
warm country- specifically a country that is warm.
somewhere warm- anywhere that is warm.
I have had enough- 十分に堪能した
Planning - ～する予定である
After retirement- 退職したら
warm country- 暖かい国
somewhere warm- 暖かい所
I'd love to move somewhere tropical after I retire.
Snowbird
I agree with you- I would love to live somewhere warm one day when I retire!
A simple way of explaining this to someone could be saying something like this: "After retirement, I want to live somewhere warm."
Here is an interesting term sometimes used in North America: snowbird.This refers to a person (usually of retirement age) who lives at home in the summer, but travels down south in the winter to a warmer climate- like a migrating bird! :)
気持ち分かります、私も退職したら、どこか暖かい所に住みたいです！
シンプルな言い方は "After retirement, I want to live somewhere warm."（退職したらどこか暖かい所に住みたい）。
北米で時々使われる面白い言葉があります：'snowbird'
これは、夏は自宅、冬になると暖かい南の地域に移り住む、渡り鳥のような（普通は定年退職後の）人を指します。
I would like to retire abroad, preferably someplace warm.
I want to move to another country when I retire.
To "retire" means to stop working and it happens at an appropriate age, usually in one's 60s. One can "retire abroad" or one can live abroad after one "retires."
You can also say "I would like to move to" or "I would like to live in" another country after I retire.
You can also use "retire" as a noun - "retirement"
Ex. I am looking forward to reaching retirement age so that I can move abroad.
"retire"（退職する）は、決まった年齢（普通は60代）に到達し仕事を辞めることをいいます。
"retire abroad" は、退職後海外に移り住むことをいいます。
あるいは、
"I would like to move to another country after I retire."（退職したら海外に住みたい）
"I would like to live in another country after I retire."（退職したら海外に住みたい）
という言い方もできます。
"retire" の名詞形 "retirement" を使うこともできます。
例：
I am looking forward to reaching retirement age so that I can move abroad.（仕事を辞めたら海外に住みたいから退職は待ち遠しい）
After retirement, I want to live somewhere warmer.
The first two sentences have the same meaning and structure with only a one word difference so you can use these two interchangeably for the same result in meaning. The words, "overseas," and, "abroad," both refer to this idea that it would be somewhere that is not your home country.
The last sentence doesn't refer to you changing countries, but simply that you want to live somewhere that has a warmer climate.
イギリス 
アメリカ合衆国 
南アフリカ 
カナダ 
