Spot the warm front

My outdoor thermometer has alerted me to an unusual temperature swing:

Yes, that's a 4°C rise in one hour. At least it's stopped raining. But there is a tornado warning about 100 km from here, so there's a lot of energy in the air right now.

Meanwhile, indoors, my fireplace caused a spike in CO₂:

Don't worry, 2,000 ppm won't hurt me. But I did get an alert about it.