Weather Advisory

What is the Allied Concrete Weather Advisory?

This is a smart-phone based weather forecasting application designed to give concrete placers and contractors an indication of the weather over a 7 day timeframe that will enable the user to assess the potential influence of the weather on the concrete being placed. It is using meteorological data that is used to generate standard forecasts and uses additional inputs for relative humidity and wind speed.

Users need to consider this application as an additional tool to be used when deciding whether to proceed with a concrete pour. As it is a forecast, things can change. It is not a guarantee that what is predicted will happen. Conversely, a good forecast may change to produce unfavorable conditions on site for all of the usual meteorological reasons, If the work is being done in an area with a specific microclimate then the weather app predictions may not apply.

How do I use this service?

Go to WxAdvisory: weather forecasts and alerts for the locations you care about. Your current location is automatically detected on smartphones with GPS functionality. If this is disabled or not available, you can get a forecast for anywhere in New Zealand by using the search box at the bottom of the page and typing in your location.

Once the location is identified and displayed, a description on the screen shows graphically the weather forecast for the next 7 days. Touch (or click) the day summary to get a detailed hourly description of the plastic cracking risk for that day. You can scroll across the screen to show all of the day in question.

On the right hand side above the daily forecast is an advisory for overnight thermal cracking.

If you are being advised of both plastic cracking and thermal cracking for the same day and subsequent evening, then the risk of overnight cracking is very high and you need to think about early entry saw cutting of the control joints.

Ask it a question

You can ask a direct question about whatever particular weather event you have in mind. Instead of typing in a location, try asking if it will rain tomorrow, or how hot it will be at 3pm?

Example questions:

Will it rain tomorrow?

How hot will it be at 3pm?

How windy will it be in Wellington on Thursday?

How cold will it be on Saturday morning?

On-site precautions

If there are predictions of plastic cracking then ensure you have Sikafilm available and you know how to use it. The risk of thermal cracking will require precautions to protect the concrete from the cold.

It may be wise to reschedule the pour if the conditions are unfavourable and can not be mitigated.


The Weather App, has been developed using the nomograph developed by the ACI Committee 305. 'Hot Weather Concreting', ACI Manual of Concrete Practice, Part 2: Construction practices and inspection, pavements American Concrete Institute, Farmington Hills, USA , 2005, and uses other data derived from international weather databases and forecasting algorithms. It is to be used as an indicator of the likelihood of cracking, and in conjunction with the user's experience and other criteria relevant to the location in question.

This weather app is suitable for lower strength concretes (up to 30 MPa) with a propensity to bleed under normalised conditions. It is not applicable to mixes that will not bleed, or those which have a very low bleed rate. Examples of these concretes are:

  • high strength concretes,
  • concretes with low water cement ratios,
  • Concretes containing SCM's such as flyash, slag or micro-silica.

As the predicted evaporation rates are calculated using forecasted meteorological conditions, actual site conditions may vary, or change at short notice. Allied Concrete Limited can not be held liable for any decisions made as to whether a pour should or could proceed based on this forecast information.