Yes it will be somewhat seasonal. Mining is ideally suited to this though because you don't really need anything beyond a source of electricity (wind, waves, biogas, whatever), some hardware and an internet connection. In particular it means you can extract energy from places where it's uneconomical to get it all the way to the grid.
Also, it's worth remembering that all large electricity grids need load balancing capacity. Today, grid operators have contracts with large consumers of power such that they can remotely shut down or spin up heavy equipment to balance moment-to-moment fluctuations in demand. For example, in the United Kingdom there's a hydropower facility called Dinorwig which pumps water up a mountain or lets it flow down in order to absorb/generate power spikes. Storage heaters and the Economy 7 tariff also incentivise people to use electricity when there's a temporary surplus and avoid it when there's a temporary shortfall.
Mining, being an activity you can switch on or off instantly, is an ideal form of load balancing - if there's a sudden unexpected drop in electricity demand for some reason, or just an anticipated drop at night, mining hardware can switch on and absorb the excess capacity reducing the need for power shedding or inefficient cooldowns of gas turbines.
Another thing to consider is if a miner is either on a flat tariff for their electricity use or if they are on a time-of-use tariff. With the latter, running a mining rig overnight during the offpeak period might be the most economical way of mining, but I'm not aware of any mining software that can tell the rig to switch on at a given time and power down accordingly just before the offpeak period finishes.
Another possibility is with a house equipped with PV panels, the user could add an option to interface with the energy meter or home automation monitor that would run the miner while the PV generation capacity is producing an average net amount minus standby power consumption and maybe an airconditioning load (air conditioner size and PV system output pending) and run it then. Use with wind turbines might be a bit trickier, though, given the erratic nature of wind, though I believe in conjunction with a battery storage system it may be more viable and could allow the mining rig to run off the battery storage system alone.