Map from Google - Sanremo

The climate of Sanrermo, a city in western Liguria, is Mediterranean, with mild and relatively rainy winters, and warm, sunny summers. The city is located in the western Ligurian coast ("Riviera di Ponente"), an area having a particularly mild climate: the average temperature of January, even 10 °C (50 °F), is found again only in southern Italy, while in summer it's rare to have hot days. It is no surprise that the city is famous for the cultivation of flowers, in addition the landscape is full of palm trees and subtropical species.
On the other hand, however, the wind blows quite frequently.
In the neighboring towns such as Ventimiglia, Bordighera, Arma di Taggia, Imperia, Diano Marina, Alassio and Albenga, the climate is similar.
Here are the average temperatures.
Average temperatures - Sanremo
SanremoJanFebMarAprMayJunJulAugSepOctNovDec
SanremoJFMAMJJASOND
Min (°C)77911151821211814108
Max (°C)131315172124272724211614
Min (°F)454548525964707064575046
Max (°F)555559637075818175706157

The rains in the Riviera di Ponente amount to about 700 millimetres (27.5 inches) per year, and follow a Mediterranean pattern, being more abundant in autumn and winter, and having a minimum in summer, when it rains very rarely.
This is the average rainfall in the nearby town of Imperia.
@prec-Sanremo
Winter in Sanremo, from December to February, is mild; in particular, sunny days are pleasant: the temperature can reach or exceed 15 °C (59 °F) when the sun shines, while the Po valley is shrouded in mist and maybe in frost. During periods of bad weather it can be a little cold, but snow is very rare: for example it snowed in February 1986 and in February 2010. Even frosts are very rare and almost always light: the temperature usually do not fall below -2/-3 °C even during the most intense cold waves, and it may very well remain above freezing (0 °C or 32 °F) for a whole winter.

Spring, from March to May, is mild and increasingly sunnier, although there are also some rainy days.

Summer, from June to August, is warm and sunny. Generally the heat is not excessive, thanks to the influence of the sea and the sea breeze: it is even rare for the temperature to reach 32/33 °C (90/91 °F), however, some sultry periods or some very hot days can not be excluded. Some weather fronts may also pass in the summer, especially in June and in late August, or on sunny days some heat thunderstorms can reach the coast from the interior, but normally the sun shines.

Autumn, from September to November, is mild and humid, with sunny days, but also periods of bad weather.

The amount of sunshine in Sanremo is very good in the summer, when clear skies prevail, while in the rest of the yar, sunny periods, which however are not lacking, alternate with periods in which the sky is cloudy. In nearby Imperia, there are 2,570 hours of sunshine annually, ranging from 4.5 hours of sunshine per day in January, to 10.5 hours in July.

San Remo

The sea in Sanremo and nearby places, becomes warm enough for swimming in July and especially in August, when it reaches 24 °C (75 °F), while in June the Ligurian Sea is still cool.
Here are the average sea temperatures.
Sea temperature - Sanremo
SanremoJanFebMarAprMayJunJulAugSepOctNovDec
SanremoJFMAMJJASOND
Sea (°C)131313141720232422191714
Sea (°F)555555576368737572666357

When to go

The best times to visit Sanremo are spring and early summer, in particular from mid-April to mid-June. Also September is a good month, especially in the first half, because then, Atlantic depressions become more frequent.
In the height of summer, in July and August it can be hot, although less frequently than in other parts of Italy.
For a beach holiday on the Western Ligurian Riviera, the best months are exactly July and August.