I was in Bolivia in March and April.
The rainy season finished later than usual, so indeed there was a lot of snow at the time.
However we could climb Huayna Potosi, with perfect conditions.
I just saw on the news that there's just been a snow storm around La Paz (which quite unusual as it is the dry season now !).
And they have -18°C in Northern Chile (close to Bolivia). So the conditions might be a bit difficult.
Nevertheless the Condoriri area (close to Huayna Potosi) is usually less wet than the Illampu area (closer to Lago Titicaca).
If you look for a good climbing agency and hotel in La Paz I can recommend some