Yes, the effects of El Nino are strongest and most reliable in the tropics. The ones near the tropical Pacific are the most certain of all, such as above normal rainfall in Kiribati (and other central Pacific equatorial islands) and below normal rainfall in Indonesia. Temperature effects are also quite reliable, and are mainly for above normal temperature in and around the warmed oceanic waters in the Pacific. After the El Nino has been around for several months, the above normal temperature applies to most of the tropics, and then, with another couple of months' delay, above normal in portions of the extratopics. Note that El Nino contributes to the increase of the global average temperature, especially the year following the onset of the El Nino. That means that even though 2015 is the warmest year on record for the globe, 2016 may be even warmer, even if the El Nino ends before the year is half over (due to the 3-6 delay of the global warming relative to the El Nino).