Yes, but when is the accumulated weather data applied to the new normal and the climate models updated?
Most people miss the point that there are changes other than the global mean temperature that are being observed for change. (here's a couple off the top of my head)
1. The north pole has moved because the weight of ice accumulated at the poles has changed. The pole has always been mobile, but the wobble has become more pronounced (just ask a figure skater what happens to their spin when they move their arms to different positions) A solid on a fixed surface has a different effect than a fluid that can shift with rotation.
2. The dissolved O2 and CO2 levels are changing in the oceans, along with the increase in ocean temperatures.
3. The amount (square miles) of thickness (getting thinner) of floating sea ice is decreasing. Watch the race between countries to claim the navigable sea lanes that are emerging.
4. Glaciers are disappearing (see point 1) not only are some land masses rising as the weight is lifted, but that water has gone somewhere (see point 5)
5. Ocean levels have risen. We live on a planet that is covered nearly 75% by water. To increase the MSL isn't just a drop in the bucket, that requires a huge amount of liquid (even factoring in the expansion occurring because the water is warmer)
I agree that a natural disaster on the order of magnitude associated with a historic Volcanic eruption can change global weather patterns, but If I remember correctly the planet bounced back to normals within 20 years the last time that happened. Unfortunately we would be burning anything that is combustable to stay warm and clearing significant vegetation to grow food, which will make matters worse... Stupid Humans
Rainy and Thunderstorms by the Beach (about 15" above sea level)