Why are my tomato blossoms falling off? Here as some answers. I was asked by one of my gardeners. I told her it is weather related and it is.

image from beckyyardboss.net    This isn't me.  

       WOW it is 2:00 PM on Thursday afternoon and it is not very enjoyable out.  The temperature is 88F(31C) and feels like 98F(37C) with the humidity.  Very little breeze, but it is partly cloudy so that helps not direct sunshine when you are outside.  BUT still, it is very hot.  We got the tall racks all onto the wagons, and down to 5 wagons, and not 7 at the beginning of the week. Now this weekend, I will start getting plants ready for the Franklin Co fair.  First load will go down Monday.  Then I will come home and organize the 2nd load.  Here we go.  I will have to water each day, but less plants will help.  I am closed now for the 4th of July and next week as we will be at the Franklin Co Fair.  Stay cool, stay safe. 

Australia family and friends for their day July 4th will be sunny with a low of 38F(3C) and a high of 59F(15C).   They are having a frost warning and flooding for east of them. Areas are relatively wet following recent rainfall. Stay dry, stay warm, stay safe.
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I had a gardener call me about her tomatoes losing their blossoms.  This is what I found out.
Gardening Aloft: Blossom Pollination
Tomato blossom drop can occur due to several factors, including poor pollination, extreme temperatures, inconsistent watering, and plant stress.
Key Causes of Blossom Drop
Poor Pollination:
Tomatoes are self-pollinating, but they still require some external agitation for effective pollination. Lack of wind or pollinators can lead to unpollinated flowers, which then drop off. To improve pollination, consider hand-pollinating with a soft brush or using a battery-powered toothbrush to induce vibrations that help release pollen. Additionally, planting flowers nearby can attract more pollinators.
Extreme Temperatures:
Tomato plants thrive in temperatures between 70°F and 85°F. High daytime temperatures above 85°F or nighttime temperatures below 55°F can stress the plants, causing them to drop blossoms. Sustained temperatures over 100°F can be particularly damaging. To mitigate this, provide shade during extreme heat and protect plants from cold snaps.
Inconsistent Watering:
Fluctuations in soil moisture can stress tomato plants. A feast-or-famine watering approach can lead to blossom drop. Aim for consistent moisture by watering deeply but less frequently, and consider using mulch to help retain soil moisture.
Plant Stress:
Stress from overcrowding, pests, or diseases can also lead to blossom drop. Ensure adequate spacing between plants to allow for airflow and pollinator access. Regularly check for pests and maintain overall plant health to minimize stress.
Nutrient Imbalance:
An imbalance in nutrients, particularly excessive nitrogen, can lead to lush foliage at the expense of flowers. Ensure a balanced fertilizer is used to promote healthy growth and flowering.
Solutions to Prevent Blossom Drop
Improve Pollination: Hand-pollinate or attract more pollinators by planting companion flowers.
Manage Temperature: Use shade cloths during heat waves and protect plants from cold nights.
Water Consistently: Maintain even soil moisture and use mulch to regulate temperature.
Monitor Plant Health: Regularly inspect for pests and diseases, and ensure proper spacing between plants.
By addressing these factors, you can reduce the likelihood of blossom drop and improve your chances of a fruitful tomato harvest.
GOOD LUCK with this, as it is hard to do because of the heat of July. 
Taken from https://www.bing.com/search?pglt=299&q=what+is+causing+the+tomatoes+to+lose+their+blossoms
Till next time this is Becky Litterer, Becky’s Greenhouse, Dougherty Iowa [email protected]  641-794-3337  cell 641-903-9365  Becky’s Greenhouse.com, Facebook, Becky Kerndt Litterer, Becky’s Greenhouse