A spring/fall cycling jersey is designed for that sweet spot between about 12–22°C (54–72°F), making it the most versatile option in a cyclist's closet. It uses midweight fabrics that provide a bit of warmth without overheating you, and many include light wind protection on the front or even removable sleeves for adapting to changing conditions.
This is widely considered the best first jersey purchase because it covers such a wide range of riding weather. In temperate climates, you can wear it comfortably for most of the year—just add a base layer underneath on cooler mornings or unzip when the sun comes out.
The main trade-off is that it won't handle extreme heat or deep cold on its own. But with smart layering, a spring/fall jersey can easily stretch from crisp autumn rides to mild summer evenings, making it the workhorse of your cycling wardrobe.