You can decide how the weather shifts overnight. In the morning, you find a blackberry vine.
You could wake up chilled. The clouds have thinned, but they still conceal the sun behind them. The air is warming, but you shiver. You pick a blackberry, cool and wet with last night's rain. It's mostly ripened except for a patch of purple one one side. You put it into your mouth, and tart berry juice mixes with rainwater and runs down your throat. It stings a bit, but it tastes good. The next one is sweeter.
You might wake up warm. The sun is bright, and the sky is clear. The heat and humidity are nearly unbearable, but you discover the blackberry vine growing in the sun before you retreat into the forest. You choose a berry that falls off in your hand. It is soft and warm, and you think for a second that it tastes like sunshine, before you remember the real sun beating down on your face.
You pick berries until you can't find any ripe ones. The vines don't let their fruit go easily. They catch your hands and arms with thorns, leaving behind stinging scratches as a warning that you choose to ignore. You stop, finally, take a breath and absentmindedly pull a blackberry thorn from your hand.
The pain startles you. A trickle of blood starts to flow down your hand, and as you move your other hand to stop it, you forget where you are. You open your eyes.
The thorn is still there. The blackberries aren't.