Leave a chocolate bar and a bag of boiled sweets on a car dashboard on a hot day and only one of them is coming back as a puddle. The difference isn't really about which sweet is more "delicate" — it's about what each one is structurally made from.
Chocolate: a fat with a genuinely low melting point
Chocolate's structure depends on cocoa butter, a fat that's solid at normal room temperature but has a melting point not far above it — comfortably within reach of a hot car, a sunny windowsill, or a parcel left on a doorstep in summer. Once cocoa butter melts, the whole structure holding the chocolate's shape goes with it, which is why chocolate is the sweet most associated with heat damage, and why mail-order chocolate is sometimes packaged or timed differently in warmer months.
Boiled sweets: no fat to melt in the first place
Boiled sweets are essentially pure sugar, cooked and cooled into a hard, glass-like solid with almost no fat and very little water. That sugar glass doesn't have a low melting point the way a fat does — it stays solid at any temperature a UK summer, or a hot car, is realistically going to reach. The risk for boiled sweets in heat is a different one: ambient humidity making the surface sticky, which is a separate moisture effect rather than melting.
Gummies: softer, not liquid
Gummy and jelly sweets sit in between structurally. They're a gelatine or starch gel, not a fat, so heat doesn't melt them the way it melts chocolate — but warmth does loosen the gel and accelerate moisture movement in or out of the sweet, which is why gummies left somewhere hot tend to turn softer, tackier or sticky rather than staying firm, without ever becoming liquid the way chocolate does.
What this means in practice
Chocolate is genuinely the one to keep out of direct heat and sun if you want it to arrive and stay in shape; boiled sweets are the most heat-tolerant format in a normal UK summer; gummies sit in the middle, more prone to going soft than melting outright.
Frequently asked questions
Why does chocolate melt in heat but boiled sweets don't?
Chocolate relies on cocoa butter, a fat with a low melting point. Boiled sweets are a fat-free sugar glass that stays solid well beyond typical summer heat.
Why do gummies go sticky instead of melting?
They're a gel, not a fat, so heat loosens and speeds moisture loss or absorption in the gel rather than melting it outright.
Can chocolate really arrive melted in the post during summer?
Yes — a hot delivery van or doorstep in direct sun can exceed cocoa butter's melting point, which is why dispatch and packaging are sometimes adjusted in warm weather.