By the Numbers
By the Numbers: How a Seven-Day Average Explains Heat-Related Calls
Use seven UKHSA daily NHS 111 call counts to calculate a transparent average and show how a moving window changes.
Daily data can move sharply during a heatwave. UKHSA's dashboard recorded 375 NHS 111 triaged calls relating to heat exposure or sunburn on 9 July 2026, but one day's peak does not describe the whole week.
A simple average gives a more stable summary. This article uses the Average Calculator to turn seven published daily counts into one weekly figure. It is a statistics lesson, not an assessment of personal health risk.
The story number
The UK Health Security Agency's summer seasonal environmental conditions dashboard publishes daily NHS 111 triaged-call counts.
For 8 to 14 July 2026, the displayed daily values are:
| Date | Calls |
|---|---|
| 8 July | 249 |
| 9 July | 375 |
| 10 July | 364 |
| 11 July | 349 |
| 12 July | 316 |
| 13 July | 210 |
| 14 July | 159 |
By 19 July, the daily count displayed was 73.
The number to run
The arithmetic mean is:
`mean = total of all observations ÷ number of observations`
For a moving average, the same calculation is repeated as the time window advances. The oldest day drops out and a new day enters.
The assumptions
We use the seven daily counts from 8 to 14 July as one fixed, reader-reproducible window. We do not attempt to reproduce every processed series or baseline shown elsewhere on the UKHSA dashboard.
The input list is:
`249, 375, 364, 349, 316, 210, 159`
Run the numbers
Add the seven counts:
`249 + 375 + 364 + 349 + 316 + 210 + 159 = 2,022`
Divide by seven:
`2,022 ÷ 7 = 288.86`
The average daily count across this selected week is therefore about 289.
Compare that with individual days:
- 9 July peak: 375, about 86 above the selected-week mean
- 14 July: 159, about 130 below the selected-week mean
The mean sits between them and summarises the full set without claiming that any one day was “typical.”
Why the window matters
Suppose we move the seven-day window forward by removing 8 July's 249 and adding 15 July's 107:
`2,022 - 249 + 107 = 1,880`
`1,880 ÷ 7 = 268.57`
The average falls from about 288.86 to 268.57, even though six of the seven observations are unchanged. That is the mechanics of a moving average: it responds gradually as new values replace old ones.
What the result means
Daily counts and averages answer different questions:
- A daily count shows the activity recorded on one date.
- A seven-day average smooths short-term peaks and dips.
- The chosen window can affect the result, especially when values are changing quickly.
Neither measure explains why calls occurred. It also does not show the number of unique people affected, clinical severity or population prevalence.
Try your own numbers
Paste any seven consecutive daily values into the Average Calculator. Then replace the first value with the next day's count to see how the mean changes.
The Standard Deviation Calculator can show how spread out the same observations are. Use the Percentage Calculator only when the numerator and denominator answer a clearly defined question.
Caveats and source notes
- UKHSA describes these as syndromic-surveillance data for NHS 111 triaged calls, not diagnoses or prevalence.
- Service use, reporting, processing and the dashboard's own methodology affect interpretation.
- Our 8-14 July mean is calculated directly from the seven displayed daily counts; it is not a substitute for UKHSA's processed trend and baseline measures.
- Do not use this example to infer individual risk or decide on treatment. Follow official health guidance.
Source: UK Health Security Agency, Summer seasonal environmental conditions, data accessed 24 July 2026.
