Map from Google - Meknes

The climate of Meknes, a northern Moroccan city, located at 500 metres (1,600 feet) above sea level, is subtropical, with mild and quite rainy winters, and hot and sunny summers. The climate is quite similar to that of Marrakesh, although it's a bit cooler (on average the temperature is lower by 1/2 degrees Celsius in winter, and even 3/4 in summer), and rainier, given its more northern position.
Here are the average temperatures.
Average temperatures - Meknes
MeknesJanFebMarAprMayJunJulAugSepOctNovDec
MeknesJFMAMJJASOND
Min (°C)677912151818171396
Max (°C)161719202428333230252016
Min (°F)434545485459646463554843
Max (°F)616366687582919086776861

Rainfall is not so scarce: it amounts to 570 millimetres (22.5 inches) per year, and occurs mostly from October to April; some rain, usually in the form of downpour, can occur also in May, and more rarely in June and September. The decent amount of rainfall and the presence of rivers that descend from the Atlas mountains makes it possible to cultivate the land, so the landscape is quite green. This also applies to the nearby city of Fez, which has a similar climate.
Here is the average precipitation.
Average precipitation - Meknes
MeknesJanFebMarAprMayJunJulAugSepOctNovDecYear
MeknesJFMAMJJASONDY
Prec. (mm)7580707040102210458085569
Prec. (in)33.12.82.81.60.40.10.10.41.83.13.322.4
Days91091074124791082

Winter, from December to February, is mild: the average temperature in January is 11 °C (52 °F). However, it's often cold at night, so that lows can approach 0 °C (32 °F), and sometimes even light frosts may occur, around -2/-3 °C (27/28 °F). Sometimes it can get quite cold during the day as well, with highs around 10 °C (50 °F). In January 1981, even a snowfall occurred.
There can be long periods of good weather and no rain, with very mild temperatures, around 20 °C (68 °F), but also periods of bad weather, with rain and cloudy skies.

Spring, from March to mid-June, is mild or pleasantly warm, but it is also quite rainy until April or mid-May, when it can still get a little cold at night, with minimum temperatures around 5 °C (41 °F). At other times, the first days with southerly winds can occur, in which the temperature can reach 35 °C (95 °F) in May, and 38/40 °C (100/104 °F) in June.

Summer, from mid-June to August, is hot and sunny, with very rare thunderstorms. The average temperatures are not so high, and in general nights are still quite cool; in fact sometimes the minimum temperature can drop below 15 °C (59 °F). However, periods of hot weather are possible, when the wind blows from the desert. In the hot summer of 2012, the temperature touched 45 °C (113 °F) in late June and in July, and 44 °C (111 °F) in August.

Autumn, from September to November, is initially hot, though already with cool nights, then becomes progressively more cool and rainy. In the first half of October, the temperature can still exceed 30 °C (86 °F), while in November it gets cold at night.

The amount of sunshine in Meknes is adequate from November to February, when there is no shortage of sunny days, which, however, alternate with cloudy periods, while in spring and autumn it's good, and in summer it's very good, given that clear skies prevail.

Meknes

When to go

The best times to visit Meknes are spring and autumn, especially the months of April and October, although they are quite rainy. In May, in the first half of June and the second half of September, the heat is generally pleasant or at least bearable, but we can not exclude some days with intense heat, due to the desert wind. In mid-summer, in July and August, it depends on the period: sometimes the heat is bearable, but there is also some chance of periods of very hot weather.
A sweatshirt for the evening can be useful also in June and September; those who suffer from the cold can bring one also in July and August.