If I react to a temporary trigger with a card in my hand, does this use my fresh awakened runes?

Yes, you can use your fresh, readied runes to pay for a card played in response to a Temporary trigger.

According to Rule 315.1.a, you ready all your exhausted game objects (including runes) during the Awaken Phase, which occurs at the very start of your turn. Because the Temporary trigger occurs during the Beginning Phase (which happens after the Awaken Phase), your runes are already readied and available to be exhausted to pay for the costs of the card you play in response.

Sequence of Events

1. Awaken Phase: You ready all your exhausted game objects (Rule 315.1.a).
2. Beginning Phase: The Temporary ability triggers and is placed on the chain (Rule 742.1.b).
3. Reaction: You play a card from your hand in response to the Temporary trigger.
4. Pay Costs: During the process of playing that card, you exhaust your now-ready runes to pay the required energy/power costs (Rule 357.1).

This interaction is consistent with RiftJudge FAQ #8926, which confirms that you can react to a Temporary trigger and that your runes are available to be used because the Awaken Phase has already concluded.