Spring arrives at 6:45 p.m. today which means the sun, at that time, is at 90 degree above the horizon, directly over the equator. There are two equinoxes every year – in March and September – when the Sun shines directly on the equator and the length of night and day are nearly equal, but not quite.

At its peak, from now until the first day of summer, the sun will continue to appear higher and higher in the sky. Once we are past June 21st, the sun will very slowly begin its decline towards the autumnal equinox and the following season which shall not be named.

Daylight will continue to increase into mid-June, but the pace of increase peaks on the first day of spring. By the time we get to June the rate at which we see daylight increasing, will slow. Put another way, the gap between sunrise and sunset reaches its maximum on the first day of summer.

The reason why our warmest day of the year isn’t on the first day of summer is because of seasonal lag. This concept means the amount of heating of the earth will continue to increase even beyond the longest day of the year. We generally reach the hottest period of summer in late July or even early August.

While astronomical spring may finally be here, the weather will continue to be on the cool side through the end of the month. While some warm days are certainly likely before the 31st, I still don’t see any stretches of really warm weather ahead. It’s likely we will have to wait until sometime after the Passover/Easter period before we truly start thinking spring is here.

Have a great first weekend of spring, no matter what the weather.