National City (CA) Temperature by Month
The average annual maximum temperature in National City, California, United States of America is 23°C (73°F), with daytime highs ranging from 19°C (66°F) in December to 27°C (81°F) in September. This page covers monthly averages, day-night differences, and how National City compares to cities worldwide.
National City Monthly Temperatures
The climate in National City experiences moderate temperature changes, with mild shifts between seasons. At night, temperatures range from 18°C (64°F) in September to 9°C (48°F) in December.
The chart below illustrates the average maximum day and minimum night temperatures in National City by month:
The coldest point of the day usually falls between 4 AM and 6 AM, with temperatures peaking around 3 PM. September, the city's warmest month, gets 253 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: National City vs the United States of America
The map below shows the annual temperature across the United States of America. You can also select individual months if you want to compare a specific time of year.
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National City vs World: Temperature Compared
National City's average annual maximum temperature is 23°C (73°F). To put that in context, here's how it compares to a few well-known destinations:
Lisbon, Portugal averages 21°C (70°F) annually — warm summers, mild winters, and rain mainly in the cooler months.
Toronto, Canada averages 13°C (55°F) annually, with cold snowy winters balanced by genuinely warm summers.
Chicago, USA averages 15°C (59°F) annually — known for extreme seasonal swings, from bitterly cold winters to warm summers.
Brisbane, Australia averages 26°C (79°F) a year, with warm winters and hot, humid summers.
What Does the Temperature Feel Like in National City?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In National City, December is the coolest month, with average highs of 19°C (66°F) and humidity around 64% — considered high. In September, the warmest month, temperatures average 27°C (81°F) with 74% humidity — conditions that feel high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
Seasonal temperature shifts influence more than just how warm it feels — they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.
Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in National City this rarely lasts long on the ground.
For more on National City's weather — including monthly rainfall, sunshine hours, and humidity — visit our National City climate page.
