好天气英文可以说是 good weather。来源是从英文单词 good 和 weather 组合而来。例句：

It's a beautiful day! The weather is so good today.

(今天真漂亮！天气真好。)

I hope the good weather continues for our picnic tomorrow.

(希望明天野餐的时候天气还是这么好。)

The forecast is calling for good weather all week.

(预报称本周天气都很好。)

注意：good weather 并不是唯一表示好天气的英文表达方式，也可以使用其他词组来表示，如 nice weather、favorable weather 等。