How long is a battery expected to last in an outdoor environment?

Battery life is highly dependent on the operating temperature. The higher the operating temperature of the battery, the shorter the expected battery lifetime. If the average air temperature is about +40° C (operated at year-round high temperature, such as in the tropics), the expected battery lifetime is about two years. If the average air temperature is around +20° C (moderate temperature found in most areas), the expected battery life is about four years. In cold climates (near 0° C year-round), the expected battery lifetime is about six years.
Another major factor that determines expected battery lifetime is the depth of discharge and frequency of charge and discharge cycle.
For example, if a battery is fully discharged and recharged on a daily basis (such as an outdoor UPS system powered by street light circuit that is ON for eight hours and OFF for 16 hours on a daily basis), then battery lifetime is 350 full charge/discharge cycles or about one year.
However, if a battery is discharged to only 50% level then recharged to 100% level on a daily basis (so that only half of the stored energy in the battery is discharged and recharged on a daily basis), the same battery lifetime is 1,000 charge/discharge cycles, or about three years.
If only 25% of the stored energy in the battery is discharged then recharged to 100% level on a daily basis, then the expected battery lifetime is 2,000 charge/discharge cycles, or about six years, assuming that the operating temperature condition is also near 0° C at which maximum battery lifetime can be expected.