The seasons can greatly effect the methods we use to fish for muskie. Muskie are in different modes with different concerns during the different seasons and therefor require changing techniques to gain their attention.
Spring muskie fishing:
Spring muskies are in a chaotic phase. They are generally post-spawn and are recovering. Their ranges can be from shallow to deep, higher in the water to low, in the weeds or in the deep lake basin. They also tend to have less aggressive feeding behaviors. To find these muskie look for warmer waters, This often means shallow, southern-facing bays as this water will warm faster and draw more of the life to it in the springtime. It is recommended to use smaller lures.
Pre-summer Muskie fishing:
Pre summer in the muskies world is anywhere before mid-June. This can be a tough time to catch muskies as well. The water temperatures haven't really warmed up enough to create aggressive behaviors and the muskie are still somewhat beat up from their spawn. Similar tactics to the spring time muskie can work with smaller lures. Look for schools of baitfish and work the edges.
Before we get to summer there is a period of time coming that many muskie fishermen having been waiting for all winter. This is that first stretch of warm, hot weather that really kicks off the water temperature rising to it's summer temperature. Watch this window closely and hit the water when it comes. Muskie tend to go into an extended feeding frenzy during this time and become highly aggressive. Any type of lure can work but the best bet is to watch where their food sources are. Often the weed beds and other structure that smaller baitfish use for cover haven't fully developed yet and you might get more schools of baitfish in congregating in open water. Look for these schools and fish them hard.
Muskies are in their normal patterns during this time and the techniques you use depend more on current weather then a specific seasonal strategy. Early mornings and late evenings along with night fishing will give you the best results. If you do fish during the days when the sun is high and temperatures are greatest, you'll have better luck looking deep and off shore or just outside the breaklines and drop-offs.
Late Summer/Early Fall:
In general and depending on what lakes you're fishing, not much has changed. If that is the case, continue your summer fishing techniques. For those of you on lakes that cool of sooner or start displaying a seasonal change, its time to switch to fall muskie techniques.
Watch for the turnover - this is a period of time when surface temperatures have cooled enough to be heavier then the deeper waters causing a reversal. During this phase the muskie will be less active along with all other lake life. However, shortly after this happens muskie fishing gets hot all the way to ice-over. Muskie start sensing the temperatures changing and they know winter is on it's way. They begin to go into fatty mode and more or less put a feedback over their snouts. Muskie are usually at their most active and aggressive behaviors during this time and any fishing method can work here. Live bait is a popular option and many drop suckers on quick strike rigs(LINK). Topwaters, crankbaits, jerkbaits, spinners and more all work at the right time now. The best advice is to watch the baitfish and other lake life. If you're seeing less life in the shallows and baitfish schools out deep, drop suckers around it or use cranbaits to work the edges. When there is action around the weed beds in the morning and evening use shallow jerkbaits or surface lures to work those edges. Concentrate on the diverse breaks in the weedlines as this is where muskie are waiting to ambush their prey.