As Thursday unfolds, Houston residents mark the winter solstice, ushering in the shortest day of the year and the official onset of astronomical winter. Yet, the weather in Houston seems to defy the traditional winter chill, with temperatures holding steady in the mild range as the city eases into the last weekend before Christmas.
Meteorological winter commenced on December 1, but the astronomical winter begins Thursday evening as the Earth’s northern hemisphere reaches its maximum tilt away from the sun. Despite this celestial occurrence marking the beginning of winter in various cultures, Houston’s weather on Thursday remains uncharacteristically mild, challenging the conventional expectations of a winter solstice.
Distinguishing between meteorological and astronomical winter, meteorological winter aligns with calendar months, beginning on December 1 and concluding on the last day of February. On the other hand, astronomical winter, starting sometime between December 20 and December 22 each year, extends until about three months later, culminating with the spring equinox in March. The National Weather Service and weather scientists opt for meteorological seasons for consistency in data collection and record-keeping, given the shifting dates of astronomical seasons.
During the winter solstice, the northern hemisphere reaches its maximum tilt away from the sun, resulting in the least amount of sunshine for the year. This tilt of the Earth’s axis, at 23.4 degrees, causes a low sun angle on the day of the winter solstice. Consequently, sunrise occurs later, and sunset happens earlier, leading to the shortest duration of daylight throughout the year. The day remains 24 hours long, but the time with daylight is reduced by nearly four hours compared to the day of the summer solstice in late June, the longest day of the year.
Despite the astronomical significance of the winter solstice, Houston’s weather refuses to conform to wintry norms. As the city moves toward Christmas, temperatures are expected to remain mild, with daytime highs approaching 70 degrees and nighttime lows settling in the upper 50s to lower 60s through Christmas Day. These temperatures, closer to late December high temperatures, deviate from the cooler, more typical December weather typically associated with this time of year.
The return to more seasonable temperatures isn’t anticipated until Tuesday, offering Houstonians an extended period of unseasonably mild weather. The Climate Prediction Center’s forecast through the start of the New Year suggests a return to normal or slightly below normal temperatures after this mild stretch.
However, Thursday’s forecast hints at a change in the weather pattern, marking the last completely dry day for a while. Rain is expected to arrive overnight, with potential light passing showers in some areas. The possibility of wet or slick roads could impact the Friday morning commute, with more widespread showers anticipated late Thursday into Friday morning as a high atmospheric pressure ridge breaks down.
As an upper-level disturbance ripples overhead through Friday evening, intermittent light showers may persist, urging those making last-minute holiday preparations to keep their rain gear close. Saturday presents a mix of rain chances, with sporadic interruptions between showers, particularly along and south of Interstate 10. Rain intensity and coverage are expected to increase for everyone by Sunday.
The Weather Prediction Center projects widespread rainfall through Christmas, with totals ranging from one to three inches likely from Friday through Sunday. Locally higher amounts are possible, raising concerns for localized flash flooding, primarily in urbanized areas and minor stream flooding due to heavier rainfall rates.
Despite the evolving weather patterns, Christmas Day forecasts have seen a trend towards drier conditions over the past 24 hours. While an isolated shower is possible, especially along and east of I-45 and south of I-10, those with outdoor plans for Christmas Day are advised to stay updated on the latest forecasts. As Houstonians navigate this atypical winter scenario, the city’s resilience to adapt to varying weather patterns remains evident, even during the festive holiday season.