If you have a day or two of free time, as well as the appropriate equipment, it is possible to hike this massive mountain. You would follow a stretch of the Pacific Crest Trail, known as the Snow Creek Route, beginning in the warm (and sometimes hot) Palm Springs desert, and ending in the cool (and sometimes bitterly cold) Pine forest atop the San Jacinto Mountain.
Put simply, this hike is not for the faint of heart. The trail has been known to be completed in a day, but with an estimated 12 hours of hiking, it is more likely you will end up having to camp around the halfway mark. The grade of the trail can sometimes reach 35 degrees, which is quite steep for such a long trek. It is recommended if you should choose to embark on this tiring voyage, that you at least pick a time of year where you won't be climbing through thick, heavy snow. Mid-Spring and early Fall would seemingly be the best times of the year, as the lower elevations aren't too unbearably hot, while the mountain tops aren't at their coldest.
As a final point, those who decide to hike Mount San Jacinto in its entirety need to be fully prepared. Bring more water than you think you'll need because it's never enough. Bring adequate clothing that you can add on in layers as you ascend the mountain, bring hiking poles or a walking stick to help you along the trail, and be sure to bring to money for the tram ride down the mountain. The only thing harder than climbing up a steep, rugged trail, is climbing down it.