Change shipping costs conditionally based on package contents.

functions.php

add_filter( 'woocommerce_shipping_packages', 'wc_ninja_woocommerce_package_rates', 20 );
function wc_ninja_woocommerce_package_rates( $packages ) {
	$is_warm_weather = true;

	foreach ( $packages as $package ) {
		$has_candy = false;

		foreach ( $package['contents'] as $cart_product ) {
			if ( has_term( 'clothing', 'product_cat', $cart_product['product_id'] ) ) {
				$has_candy = true;
				break;
			}
		}

		if ( $is_warm_weather && $has_candy && sizeof( $package['rates'] ) > 0 ) {
			foreach ( $package['rates'] as $rate ) {
				$rate->cost = $rate->cost + 10;
			}
		}
	}

	return $packages;
}