Monarch caterpillar is back!

Last year I didn't have any Monarch caterpillars come to my purposely-planted milkweed patch. T'was very disappointing. But tonight I went out to the milkweed to do the usual inspection of the undersides of the leaves, and what do I see?! A very juvenile caterpillar munching away! It seems pretty late in the summer, and if history runs true in the case o f past butterfly/caterpillar metamorphases(?) I've experienced and been fortunate enough to view here in my garden, this little creature will not make it to the chrysalis & then butterfly stage before cold temperatures set in. I'm going to try to faithfully track its progress & growth as August & September continue.
I wonder why the Monarch butterflies seem to wait until so late in the season to deposit their eggs. Actually, I haven't even seen any Monarch butterflies here in my yard anywhere this season, so I suppose I should be somewhat surprised to see the caterpillar. They are more than welcome, and I wish I could help them extend their seemingly-limited lifespan.
I feel like I offer an oasis in the pesticide-desert when I see these little critters here.