Cherry blossoms blooming in Toronto’s High Park is a sure sign spring has arrived and winter weather is in the rearview mirror. With sunny skies forecasted to begin the week, we’re that much closer to witnessing a full bloom, but how might a rainy few days impact the process?

Blossoms in High Park usually reach peak bloom between late April and early May. According to High Park’s nature centre, the cherry blossoms are now in Stage 4 of the bloom development process. While cold weather can slow things down, warmer spring weather can move the buds along quickly.

Stage 4 typically reveals flower stems that get longer, with some blossoms seen during this period. High Park’s nature centre says the cherry blossoms are vulnerable to frost at this stage, which could cause issues should temperatures continue to drop in the coming days.

In its latest update, the nature centre mentioned “We expect to reach peak bloom in High Park on Monday, April 22.”

Sakura Steve believes the first bloom in High Park could come as soon as this week.

“All we need now is just a good few sunny days, and then we should see a full bloom right around next weekend,” Sakura Steve wrote in his latest update. “That ties in with my prediction of April 18 to see the full bloom start and then continue through to the 24th, weather permitting.”

There is no vehicle or parking access to High Park during the cherry blossom peak bloom period. Only Wheel-Trans vehicles will be allowed into High Park during peak bloom.

How this week’s forecast could impact the first bloom

Since the blooming of cherry blossoms is so weather-dependent, Toronto’s extended forecast will make things tricky.

The week kicked off with beautiful sunny skies which will continue on Tuesday with a daytime high of 15 C on Monday and 13 C by this afternoon. That should speed up the process ever so slightly; however, a system is expected to bring a heavy dose of rain on Wednesday that will linger until Friday. Upwards of 50 millimetres could fall in the city by week’s end.

“Blossom development is a temperature-sensitive process. Warm weather encourages cherry trees to bloom early, while cooler temperatures delay bloom time,” High Park’s nature centre noted. “It is difficult to predict peak bloom more than 10 days in advance because it is dependent on weather conditions.”

Though subject to change, daytime temperatures could fluctuate this weekend, going from 13 C on Saturday to only 9 C on Sunday.

High Park’s nature centre says the blooming period begins when 20 per cent of the cherry blossoms are open and ends when the petals fall. Peak bloom starts when at least 70 per cent of the blossoms are open.

Once open, flowers last 4-10 days, depending on the weather conditions.

Cherry blossoms last for about a week to a half with appropriate spring-like weather, but if it rains while they are in bloom, the flower petals fall quicker, and the blooming may be over in a few days.

The City of Toronto lists other locations where cherry blossoms can be seen, in addition to High Park.