Tuesday 21st April
Monday was a day of contrasts when out and about, one minute it was very warm in the sunshine and then when the sun disappeared, it felt chilly in the brisk northeasterly breeze. The maximum temperature occurred late in the afternoon when the cloud thinned a little resulting in a high of 14.3C at 16.17, which was exactly average for April. The temperature initially during the evening began to drop away steadily, as on previous nights, but the cloud radar showed variable cloud arriving after 02.00, which saw total cover by 05.00, that slowed the loss of warmth into the atmosphere, resulting in a minimum of 3.2C at 04.46.
There were a very brief few minutes of brightness just before 07.00 on Tuesday, through thin breaks in the cloud cover, but very quickly the thick cloud was pushed across from the east. This resulted in the coolest start to a new day at 08.00 since the 13th, with a temperature of just 5.9C. There is a modest windchill this morning that when the shielded thermometer indicated 5.9C at 08.00, it felt more like 5.3C outside. The blanket of cloud is extensive over southern England that hopefully, might thin and allow some brightness as the morning progresses, however, strong sunshine for any length of time will be in short supply.
The high pressure over Iceland will dominate our weather up to and into the coming weekend. This will result in the dry conditions persisting with the wind continuing from an easterly quadrant until at least Saturday. There is hope that by Wednesday the temperature will rise above the average with more hours of strong sunshine likely due to reduced cloud cover and by Thursday, the lighter wind will make it feel much more like Spring again.
Why pollen levels are high again this week
Author: Met Office (updated from two weeks ago)
A spell of dry and sunny weather has led to rising pollen levels across much of the UK this week.
These conditions are particularly favourable for pollen release and dispersal, meaning many people are likely to notice an increase in hay fever symptoms. While some changes in the weather later in the week may ease pollen levels slightly, high or very high levels are expected to persist for several days, especially in central and southern areas.
This week also marks a key point in the tree pollen season, with birch and plane pollen becoming increasingly dominant this week, alongside ongoing ash pollen and the early beginnings of oak pollen.
Why pollen levels are high this week
Weather plays a crucial role in both how much pollen is produced and how effectively it spreads. The recent pattern of warm temperatures, sunshine and dry conditions has encouraged trees to release pollen in large quantities. In addition, breezy conditions help pollen grains disperse more widely and remain airborne for longer, increasing exposure.
Warm conditions stimulate pollen development within catkins, while dry air allows pollen to be released more easily. Without rainfall to wash pollen out of the air, levels can steadily build from day to day, which is what many people are experiencing now.
Pollen levels are high this week and are expected to remain high through to Friday.