Map from Google - Trujillo

In Trujillo, Peru's third city, the climate is subtropical desert, with a warm season from January to March, and a relatively cool season from June to November.
The city is located in the northern part of the Peruvian coast, in La Libertad region, and despite its location, about 8 degrees south of the equator, the climate is arid and very mild, due to the cold Humboldt sea current; at this latitude the climate begins to resemble that of the capital Lima. The temperature range is very small: the temperature almost never drops below 10 °C (50 °F) on winter nights, while during the day it rarely reaches 30 °C (86 °F) in the summer months. The landscape in the area is practically desert, except in areas where waterways flowing from the Andes are used to irrigate fields; to find some green areas you have to go the east, at the foot of the Andes. During the winter, however, moisture can condense into mists and droplets that can be deposited on the ground (a phenomenon called garúa). Some night and morning fogs can not be ruled out even in the summer.
Here are the average temperatures.
Average temperatures - Trujillo
TrujilloJanFebMarAprMayJunJulAugSepOctNovDec
TrujilloJFMAMJJASOND
Min (°C)182020181717161515151617
Max (°C)252625232322212020212223
Min (°F)646868646363615959596163
Max (°F)777977737372706868707273

The rains are definitely scarce: on average only a few millimeters of rain per year fall, and for long periods it never rains.
Here are the average precipitation.
Average precipitation - Trujillo
TrujilloJanFebMarAprMayJunJulAugSepOctNovDecYear
TrujilloJFMAMJJASONDY
Prec. (mm)2120000000006
Prec. (in)0.100.10000000000.2
Days

The climate of Trujillo is affected by the cycles of El Niño, the phenomenon that consists in the abnormal warming of the Pacific waters: in the Niño years the air temperature (and also that of the sea) increases, especially in the early months of the year, when there may be long periods with a practically tropical heat: for example, in February 1998 the average daily temperature has been 27.2 °C (81 °F), and in April 1983 it has been 27.5 °C (81.5 °F), with a maximum of 34.5 °C (94 °F).
Instead, as regards the rains, they tend to remain scarce or absent even in these periods (while more to the north, in the regions of Tumbes and Piura, and partly also in the Lambayeque region, see Chiclayo, in the years of El Niño even rainfall increases).
During the years of La Niña, the phenomenon opposite to that of El Niño, in winter the temperatures drop below the average, and there are long periods with highs below 20 °C, and lows below 15 °C (59 °F).
The amount of sunshine in Trujillo is decent in summer, from December to April, whereas in winter, from July to September, it becomes quite mediocre, because the Humboldt current can cause fog and low clouds.

Trujillo, Plaza de Armas

Usually, the sea in Trujillo is never very warm: it's warm enough for swimming in February and March, while it gets very cool from July to November, as it drops down to 18/19 °C (64/66 °F). However, in the Niño years, the sea in this area warms up a lot, especially in the early months of the year.
Sea temperature - Trujillo
TrujilloJanFebMarAprMayJunJulAugSepOctNovDec
TrujilloJFMAMJJASOND
Sea (°C)222323222020191818181921
Sea (°F)727373726868666464646670