Old Lyme (CT) Temperature by Month
Old Lyme, Connecticut, United States of America has an average annual maximum temperature of 16°C (61°F), ranging from 4°C (39°F) in February to 28°C (82°F) in July. Below you'll find a full monthly breakdown and a comparison with cities worldwide.
Old Lyme Monthly Temperatures
Visitors to Old Lyme can expect significant temperature changes throughout the year. Nighttime temperatures also vary widely, ranging from 19°C (66°F) in July to -5°C (23°F) in February.
The chart below illustrates the average maximum day and minimum night temperatures in Old Lyme by month:
The coolest part of the day is typically between 4 AM and 6 AM, while 3 PM is usually the warmest, when solar heating is at its peak. July, the city's warmest month, averages 293 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Old Lyme 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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Old Lyme vs World: Temperature Compared
Old Lyme's average annual maximum temperature is 16°C (61°F). To put that in context, here's how it compares to a few well-known destinations:
Athens, Greece sits at 23°C (73°F) on average, with hot dry summers and mild winters characteristic of the Mediterranean.
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.
Perth, Australia averages 25°C (77°F) annually, with a classic Mediterranean climate — hot dry summers and mild wet winters.
What Does the Temperature Feel Like in Old Lyme?
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 the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Old Lyme, February is the coolest month, with average highs of 4°C (39°F) and humidity around 63% — considered high. In July, the warmest month, temperatures average 28°C (82°F) with 68% 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.
Whether a city sits on the coast or deep inland makes a significant difference to its climate. Coastal areas tend to have more stable temperatures year-round — large bodies of water absorb heat slowly in summer and release it gradually in winter, keeping extremes in check. Cities far from the sea don't benefit from that buffer, which is why continental climates tend to have hotter summers and colder winters than their coastal counterparts at the same latitude.
For more on Old Lyme's weather — including monthly rainfall, sunshine hours, and humidity — visit our Old Lyme climate page.
