Arequipa, the "White City," sits at an elevation of 2,335 meters (7,661 feet) in the shadow of the Misti, Chachani, and Pichu Pichu volcanoes. Its geographical position creates a subtropical desert mountain climate characterized by a remarkably high number of sunny days and a significant temperature range between day and night.
Typical Weather Patterns
Arequipa is famous for having over 300 days of sunshine per year and one of the highest levels of solar radiation in the world. The climate is predominantly dry, with a short, concentrated rainy season and a long, stable dry season. Because the air is extremely dry—with humidity levels often dropping below 30%—the atmosphere is transparent, which makes the sun feel piercingly warm while shaded areas can remain surprisingly cool.
The Daily Rhythm
In the Andes, the sun dictates the temperature.
- Morning (6 AM – 10 AM): The air is crisp and often chilly. As the sun rises, the temperature climbs rapidly.
- Midday (11 AM – 3 PM): This is when solar radiation peaks. Even if the thermometer reads a moderate 22°C (72°F), the "real feel" under the direct, high-altitude sun can be much hotter. Locals often call this the "burning sun."
- Evening (5 PM – 9 PM): Once the sun sets, the temperature drops sharply. It is common for the thermal range to exceed 15°C (27°F) in a single day.
- Night (10 PM – 5 AM): The clear skies allow heat to escape back into the atmosphere, leading to cold nights, especially during the austral winter (June to August).
Seasonal Trends
Arequipa does not have four traditional seasons; instead, it is split into two primary periods.
The Dry Season (April to November)
This is the most stable time of year. Skies are almost perpetually blue, and the air is at its driest.
- Winter (June/July): These are the sunniest but coldest months. Nighttime temperatures can drop toward 5°C (41°F), though daytime highs remain a comfortable 21°C (70°F).
- Peak Heat (October/November): Statistically the warmest months, where daytime highs often reach 24°C (75°F) or more before the arrival of the rains.
The Rainy Season (December to March)
Unlike the Amazon, Arequipa's "wet" season is relatively mild. Rainfall usually occurs as brief, intense afternoon or evening thunderstorms.
- Cloud Formations: Photographers often prefer this season for the dramatic cloud formations that gather around the volcanic peaks.
- Landscape Transformation: The surrounding desert and the slopes of the volcanoes turn a vibrant green, a stark contrast to the usual arid landscape.
Regional Variations and Microclimates
The city itself is a relatively stable basin, but nearby geographic features create local variations:
- The Volcanic Shadow: Areas directly in the shadow of Mount Misti may experience earlier sunsets and quicker temperature drops in the late afternoon.
- Colca Canyon: Travelers often use Arequipa as a base for the Colca Canyon. It is critical to note that the Canyon is much higher (up to 4,900m at top passes) and significantly colder and windier than the city center.
- Valley Breezes: During the day, valley breezes typically blow from the southwest, while at night, cooler mountain breezes descend from the northeast.
Local Phenomena and Historical Context
- The "Mini-Hole" in the Ozone Layer: Arequipa is situated under a region of the atmosphere where the ozone layer is naturally thinner. This, combined with the altitude, results in UV indices that frequently reach "Extreme" levels (11+). Locals strictly adhere to sun safety, often seeking shade during peak hours.
- Sillar Architecture & Temperature: The city’s historic center is built from sillar, a white volcanic stone. This material has excellent thermal properties; it absorbs heat during the day and releases it slowly at night, helping to regulate the internal temperature of older buildings.
- Dust Devils: In the dry season, the heating of the desert floor can create small dust whirlwinds (remolinos) in the outskirts of the city.
The "Feel" of Arequipa
The weather in Arequipa is one of contrasts. It feels "bright" and "energetic" during the day but "solemn" and "sharp" at night. Because of the low humidity, you rarely feel sweaty or damp; instead, you may notice your skin and lips drying out quickly. The air is light and thin, which can make the sun feel aggressive even when the air temperature is mild.