Weather in San Bernardino

Planning your day or a trip to San Bernardino? Here you will find the latest weather information, including detailed graphs and forecasts for the near future.

The climate of San Bernardino can be described as warm and sunny, with distinct Mediterranean features. This Californian city is characterized by dry weather throughout most of the year, making it an attractive destination for heat lovers. Here, you will not encounter severe frosts, and the total amount of rainfall remains quite moderate even during the wettest months.

The seasons here are quite distinct. Summer in the city is hot and arid: in July and August, the thermometer often rises above 30°C during the day, and rain is almost entirely absent. Winter, on the other hand, is mild and comfortable, with average daytime temperatures around 16°C, although nights can be cool. It is the winter period and early spring (especially March) that account for most of the overcast days.

The transitional seasons, spring and autumn, offer the most balanced conditions for travel. April, May, and October bring pleasant warm weather without the exhausting summer heat, which is ideal for long walks and sightseeing. Overall, when travelling to this region of the United States, you can count on an abundance of sunshine and clear skies almost all year round.

The climate in San Bernardino is characterized by a distinctly hot summer and a mild winter. The hottest months are July and August, when the average daytime temperature reaches 34°C. The summer heat here is dry, as precipitation is practically absent during this period, and nights bring relative coolness, cooling down to an average of 20°C. June and September also remain summer-like warm, with daytime highs around 30–31°C.

The winter period, falling on December, January, and February, is distinguished by quite comfortable conditions. The average temperature in these months hovers around 10–11°C. Even in the coldest month, January, daytime figures often reach a pleasant 16°C, making winter an excellent time for excursions. However, nights can be quite chilly: the thermometer often drops to 4–5°C, so a warm jacket for evening walks will be necessary.

An important feature of the local temperature regime is significant daily fluctuations. The difference between the daytime maximum and nighttime minimum is often more than 10–14 degrees. For example, in spring in April, the air warms up to 22°C during the day, and cools down to 9°C at night. Travellers should take this feature into account and dress in layers to feel comfortable as the time of day changes.

Precipitation in San Bernardino is distributed unevenly, forming clearly defined seasons. In general, the city is characterized by a rather dry climate, where prolonged downpours are a rarity. The main probability of precipitation falls on the winter months and the beginning of spring. Considering that even on the coldest nights the temperature usually remains above freezing, precipitation falls predominantly in the form of rain.

The wettest period is the first half of the year. The leader in precipitation frequency is March, when an average of 13 rainy days is recorded, although the total volume of moisture remains small (about 3 mm). January and February can also be overcast: in these months, statistics show from 7 to 8 days with precipitation. Travellers planning a trip at this time are recommended to take an umbrella with them.

Summer and the beginning of autumn are a time of drought and sunny weather. From June to October, the rainfall level tends towards zero, and the number of days when light rain may occur is minimal (from 1 to 3 days per month). This makes the summer season the most predictable for planning excursions and outdoor activities.

When packing for San Bernardino in the summer months, rely on light and breathable clothing made from natural fabrics, as temperatures often exceed 30°C and there is practically no rainfall. You will definitely need t-shirts, shorts, and open-toed shoes. Given the active Californian sun and arid climate, do not forget to put high-quality sunscreen, sunglasses, and a hat in your suitcase to avoid overheating during walks.

If your trip is planned for the winter period or early spring, the approach to your wardrobe should be different. At this time of year, the average temperature holds around 10–11°C, and nights can be quite cool (down to 4°C), so the principle of layering will become your best friend. Take jeans, sweaters, and a mid-season jacket with you. It is also worth grabbing a compact umbrella or raincoat, especially in March, when the number of rainy days increases noticeably.

Regardless of the season, you will need comfortable shoes for walking, such as trainers, for sightseeing. Since temperature changes between day and evening can be palpable even in warm months (September–October), it is always useful to have a light windbreaker or cardigan at hand. A small city backpack for water and personal items will make your excursions as comfortable as possible.