Лучше бы я не забыл варежки дома, тогда руки не дрожали бы от мороза.

Лучше бы is a very common way to express regret or “it would have been better if…”.

In this sentence, Лучше бы я не забыл варежки дома means something like:

• I wish I hadn’t forgotten my mittens at home
• It would have been better if I hadn’t left my mittens at home

So although лучше literally means better, the whole phrase лучше бы + past tense often works like English I wish... in situations of regret.

Бы is the particle that helps form the conditional/subjunctive meaning in Russian.

It often appears in sentences about:

• hypothetical situations
• unreal situations
• wishes
• regrets
• consequences that did not actually happen

Here the speaker is talking about an unreal past situation:

• In reality, they did forget the mittens.
• Now they are imagining the better alternative.

So лучше бы я не забыл... means if only I hadn’t forgotten...

And руки не дрожали бы... means my hands wouldn’t be shaking...

In Russian, the conditional/subjunctive is usually built with:

• past tense form
• plus бы

That is true even when English might use something like hadn’t forgotten or wouldn’t be.

So:

• не забыл бы = would not forget / would not have forgotten, depending on context
• лучше бы я не забыл = it would have been better if I hadn’t forgotten

Russian does not use a special separate verb form like English does. It uses the past tense + бы pattern.

This is about aspect.

• забыть = perfective
• забывать = imperfective

Here забыл is used because forgetting the mittens is seen as a single completed event: the speaker left home without them.

So не забыл варежки дома means:

• didn’t forget/leave the mittens at home

If you used не забывал, it would sound more like:

• wasn’t forgetting
• didn’t use to forget
• or some repeated/process meaning

That does not fit this situation as well. The sentence needs the idea of one completed mistake, so забыл is natural.

Because the second clause is also hypothetical/unreal.

The full idea is:

• If I hadn’t forgotten the mittens at home
• then my hands wouldn’t be shaking from the cold

Russian commonly marks each unreal clause with бы:

• Лучше бы я не забыл варежки дома
• тогда руки не дрожали бы от мороза

So the first part expresses the unreal better alternative, and the second part expresses the unreal result.

Again, this is aspect.

• дрожать = imperfective, to tremble/shake
• задрожать = perfective, to start trembling

Here the speaker means an ongoing state/result:

• my hands wouldn’t be trembling/shaking

That is why дрожали бы is better. It describes the continuing condition of the hands.

If you said задрожали бы, it would focus more on the moment when the hands started to shake.

Russian often omits possessive words like my, your, his when the meaning is already obvious, especially with:

• body parts
• clothing
• personal belongings

So руки не дрожали бы naturally means:

• my hands wouldn’t be shaking

Russian does not need to say мои руки unless the speaker wants extra emphasis or contrast.

Compare:

• У меня болит голова. = My head hurts / I have a headache.
• Я помыл руки. = I washed my hands.

This is very normal Russian usage.

Варежки are mittens.
Перчатки are gloves.

So the sentence specifically says mittens, not just handwear in general.

That choice also fits от мороза well, because mittens are strongly associated with very cold weather.

Here дома means at home.

So:

• забыл варежки дома = left/forgot the mittens at home

This is a fixed and very common adverbial use:

• Я дома = I am at home
• Оставил ключи дома = I left the keys at home

By contrast, в доме means in the house/building, focusing more on the physical location inside a house.

So in this sentence, дома is the natural choice.

In natural English, the best interpretation is usually:

• left the mittens at home
• or forgot my mittens at home

Russian забыть что-то где-то often means that you accidentally left something somewhere because you forgot it.

So the idea is not just that you mentally forgot about mittens while being at home. It means you went somewhere without them because you left them behind.

От + genitive often expresses a physical cause:

• дрожать от холода = to shiver from the cold
• покраснеть от стыда = to turn red from shame
• плакать от боли = to cry from pain

So от мороза means:

• from the frost
• more naturally in English, from the cold

It emphasizes the direct physical cause of the trembling.

Yes, a version with если бы is possible, for example:

• Если бы я не забыл варежки дома, руки не дрожали бы от мороза.

That means:

• If I hadn’t forgotten my mittens at home, my hands wouldn’t be shaking from the cold.

But лучше бы adds a stronger feeling of regret:

• Лучше бы я не забыл... = I really wish I hadn’t forgotten...

So the actual sentence is not just a neutral condition; it sounds more emotional and personal.

Тогда here means then.

It links the imagined cause and result:

• Лучше бы я не забыл варежки дома, тогда руки не дрожали бы от мороза.
• If only I hadn’t forgotten the mittens at home, then my hands wouldn’t be shaking from the cold.

It helps make the consequence explicit.

Russian often uses тогда in these kinds of conditional or counterfactual sentences.

The basic meaning would stay the same with some word-order changes, because Russian word order is fairly flexible.

For example, you could also hear:

• Лучше бы я дома не забыл варежки...
• Тогда бы руки не дрожали от мороза.

But the original order is very natural.

Word order in Russian often changes for:

• emphasis
• focus
• rhythm
• contrast

In the original sentence, the flow is clear and conversational: first the regret, then the consequence.

Russian usually just states the noun directly when it is clear:

• руки не дрожали бы = my hands wouldn’t be shaking

Using a pronoun instead would usually be unnecessary or even awkward here.

Russian often prefers repeating the noun or simply naming the relevant body part rather than inserting an extra pronoun the way English sometimes might.

It is understandable and natural overall, especially in conversational Russian.

A very idiomatic English translation would be:

• I wish I hadn’t left my mittens at home; then my hands wouldn’t be shaking from the cold.

A Russian speaker might also say similar versions such as:

• Лучше бы я не забыл дома варежки — руки бы не дрожали от мороза.
• Если бы я не забыл варежки дома, руки бы не дрожали от холода.

So the given sentence is a good example of how Russian expresses regret about a past mistake and its unpleasant result.