It is recommended for producers to delay anhydrous ammonia applications until soil temperatures drop below 50 degrees F, since the conversion of ammonium to nitrate slows considerably below 50 degrees; however, it is wise to wait until soil temps have remained under 50 degrees for a week or so.  Nitrification inhibitors may be used to apply the fertilizer on warmer soils, but be sure to follow product recommendations and restrictions.

Currently, soil temperatures at a 4" depth under bare soil are in the low 50s in western NE to the upper 50s and low 60s in the southeast.  Soil temperatures, especially under bare soil can fluctuate quite a bit from day to day AND from morning to afternoon.  

Current soil temperatures can be found at the Nebraska Mesonet (mesonet.unl.edu), which is part of the Nebraska State Climate Office or can be found at CropWatch (cropwatch.unl.edu).  These soil temperatures are the average of the entire day, so take that into account, if you are taking your own soil temperatures at a single point during the day.  There can be quite a difference between the two.

With harvest quickly winding down, you may want to get moving on anhydrous applications, but the forecast for the next 10-14 days does not look like soil temperatures will drop very fast.  The Climate Prediction Center 8-14 day outlook has a 70% probability for Nebraska having above normal temperatures for that time period.  The normal daily high to start November is in the upper 50s.
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*Anhydrous ammonia applications in the fall are not recommended for coarse textured soils due to leaching potential or areas with other application restrictions.  

The Good
     The temperature pattern over the last 30-60 days has been quite favorable for Nebraska. We had some days that reached the upper 90s, but, overall, the temperature pattern has been near to slightly above normal for most of the state. September started with cool temperatures, but the last week or two has yielded some of the best weather Nebraska has to offer.

The Bad
     After a rather wet growing season for Nebraska (except for a few locations), we have recently turned dry. Even though many of the crops are mature, late-planted and long-season crops were still using moisture over the last few weeks. Over the last 30 days, portions of central and northwest Nebraska were the driest with less than a half of an inch of precipitation, with a few bands of higher amounts. In general, the state dried out significantly west of Grand Island. This may shorten the grazing season on some pastures and may have aided in early senescence in dryland fields.

The Outlook
     Temperatures will gradually cool down the rest of this week and have multiple chances for precipitation. The coldest day will be Thursday and best chance for frost is Friday and Saturday morning.  It looks like a VERY good chance of sub 32°F temps for the western half of the state with mid 20s in the far west. The big weather system will slide east through the weekend and we will begin to warm up and dry out. The weather will remain relatively quiet and uneventful most of next week, so should have another long streak of good harvest weather. Temperatures will be warm during the day and cool off during the night, so get used to running your heater and A/C in the same day. 
     Looking further out, we may settle into a pattern of these deep systems moving through every one to two weeks or so, and each one will bring in cooler temperatures than the previous.  The Climate Prediction Center (CPC) is forecasting generally above normal temperatures for Nebraska for October 10-18, as well as their October outlook that gives us slightly higher odds for above normal temperatures. Precipitation is a little less confident and will most likely be near to below normal for the rest of the month, depending on the speed of some of the upcoming frontal passages. There seems to be some confidence that we will not see a big wash-out over the next couple weeks.
     La Niña is becoming less of a factor, thus it is not discussed and the winter forecast is a coin toss for Nebraska.
 
Tyler Williams, Nebraska Extension Educator
Cropping Systems and Climate Resiliency
tyler.williams@unl.edu, agclimatenebraska.weebly.com