April brings a mix of warm days and cooler earlier evenings, a reminder that autumn is now with us. Easter and its attached school holidays bring to many of us the last chance for enjoying a good sail before the shorter days of winter sets in.

The internet is abuzz with several commentators reporting that there may be a switch to an extreme El Nino later this year. For now, relax. Indications are that, during April and into May, the Tasman Sea /New Zealand area weather is likely to be close to normal.

Our friends at tropical tidbits.com mainly watch tropical cyclones. They also give access to some climate models which show outlooks for the month of April based on current trends.

These are called anomalies and they indicate how this April may vary from normal.

In this map the isobars show the averaged weather forecast for April. Note how in April, on average, the west-southwest winds of winter reach as far north ad Cook strait, and a High centred near the Australian Bight noses a ridge of relatively light winds onto the Bay of Islands. Daily weather pattern shuffle around this idea.

The shading shows expected difference from a normal April. The red and brown areas over Papua New Guinea are above normal — but only by small amounts. And the blue shadings between Solomons and Tonga are below normal. Note that these are over a low-pressure area (the South Pacific convergence zone) and so this is expected to be accentuated in April.

This blue shading extends as far south as the Bay of Islands but there it is rather weak. The isobars indicate average winds over Bay of Islands in April are light southwest winds, and the anomalies suggest a possible swing towards southeast winds, so the result may be southerly winds…a dry direction.

Indeed, when we look at the forecast rain anomalies for April, the Bay of islands anomalies are negative/yellow.