2025 Toronto Winter Weather: What Tree Owners Need to Know
Toronto’s winters are known for their variability, but 2025 is shaping up to be colder than average. While typical temperatures range from 3°C to -7°C between December and March, this winter has already seen prolonged cold spells and lows reaching -15°C, driven by the influence of a polar vortex.
The effects of La Niña suggest that below-average temperatures will persist through the season, with heavier-than-normal snowfall expected March following a drier-than-usual January.
For tree owners, these weather shifts matter. Sudden drops in temperature can increase stress on trees, particularly younger or weakened specimens. Understanding how these patterns affect trees is key to ensuring their resilience through winter and into the growing season.
What Does This Winter’s Weather Mean for Trees?
Extreme cold can result in frost cracks, sunscald, and brittle wood, increasing the risk of breakage. This is especially true for younger trees, thin-barked species, and trees that have sustained past stress. Tree owners can mitigate damage by wrapping vulnerable trees and ensuring proper structural pruning before major snowfalls.
Cold weather also increases the likelihood of branch failure, particularly after heavy snowfall or wind events. Arborists often see an uptick in storm-related tree damage during late winter when brittle branches give way under accumulating snow and ice. Homeowners concerned about tree stability should schedule winter pruning or hazard assessments before the next major snowfall.
How Does Cold Affect Tree Species?
Young trees and those with pre-existing damage are more vulnerable to extreme cold and frost cracking. Sunscald or Southwest Injury, caused by sudden temperature shifts that damage bark cells, is a risk for thin-barked trees such as ash, oak, linden, willow, maple, birch, honey locust, and fruit trees.
Trees in urban environments like Toronto also face additional stress from road salt and runoff, which can damage roots and lead to moisture imbalances in the soil. Snow accumulation from plowing or shoveling can also compact soil around trees, reducing oxygen flow to the roots.
Does Cold Affect Deciduous and Coniferous Trees Differently?
Losing leaves in fall helps protect most large shade trees from the effects of winter. If snow and ice built up on leaves, the tree would bear much more weight from the precipitation. This could lead to additional branch or even trunk breakage.
For conifers like cedars, yews and juniper, needles don’t have the same amount of surface area to collect snow or ice. The shape of some coniferous trees also helps protect them: the triangular or pyramidal shape helps keep snow from collecting on the tree. Snow that does collect actually helps shelter needles from sunlight in the winter.
That being said, large hedges can be very easily damaged by snow and ice. Emerald Cedars are particularly prone to damage, as are formal hedges squared or flat on top. If you see snow or ice on your hedges, be sure to knock it off as quickly as possible to ensure no hedge repair or restoration is required.
Winter and Soil Conditions
Snow is actually beneficial for soil conditions in your yard. Snow helps restore nutrients — nitrogen and sulphur — to the soil. That’s why it’s sometimes called a ‘poor man’s fertilizer.’
Snow cover helps insulate the ground and a deep snow cover can lead to an earlier ground thaw. The moisture from the snow also helps moisten soil for spring growth. Snow helps protect roots against cold temperatures and promotes healthy bacteria and insect activity in the soil, leading to root growth.
Freeze-thaw cycles can disrupt this balance, though, leading to too much or too little moisture in the soil. Homeowners can react to a winter with numerous freeze-thaw cycles by being sure to fertilize their trees or hedges in late winter or early spring. This can help restore nutrients to the soil and encourage growth.
What Do Winter Conditions Mean for the Rest of 2025?
Heavy snowfall this winter could lead to a strong water supply for the growing season, as melting snow replenishes groundwater and stabilizes soil moisture. Conversely, a drier winter could increase drought stress for trees, particularly in urban settings where irrigation is less frequent.
From a pest and disease perspective, prolonged cold snaps are beneficial, as they help reduce overwintering pest populations. Boxwood moth, spongy moth, and other invasive species may see reduced numbers following a particularly cold winter. However, pathogens such as oak wilt—currently present in Southern Ontario but not yet confirmed in Toronto—can remain viable despite winter temperatures, meaning tree owners should continue monitoring for early signs of infection.
What Else Do Freeze-Thaw Cycles Do?
One consequence of increased freeze-thaw cycles is heavier road salt use, which can impact trees growing near sidewalks, driveways, and roadways. The frequent application of salt, followed by rain or melting snow, leads to high salinity levels in the soil, which can impair root function and nutrient uptake.
For tree owners, preventative measures such as barriers, alternative de-icers, and strategic soil amendments can help mitigate long-term salt damage. Monitoring trees for salt stress symptoms—such as scorched leaf edges in spring—can help catch issues before they escalate.
Keep On Top of Winter Tree Care
If you need to wrap small, young, or thin-barked trees or small shrubs, late fall and early winter in November-December is the best time for wrapping, but your trees can still benefit from late wrapping if you can stand the cold.
Tree owners concerned about storm damage, structural instability, or signs of frost stress don’t need to wait until spring to take action. Certified arborists work year-round and can assess winter tree conditions, provide risk evaluations, and conduct necessary pruning or removals.
Winter tree removals are sometimes necessary for dead, dying, or structurally unsound trees, particularly if they pose a hazard to property or public safety. However, not all damaged trees need to be removed—cabling and bracing can help support weakened limbs, extending the life of trees that might otherwise be at risk.
Winter Is Here: Make Sure Your Trees Are Prepared
Winter can be tough on Toronto trees, but proactive care ensures they enter the upcoming spring season strong and healthy. If you’re concerned about the impact of Toronto’s winter on your trees, book a professional arborist assessment today.
