Thermal Discomfort Index Report

Executive Summary

Key Finding

Thermal discomfort conditions affect Cyprus for 47.6% of the forecast period (101 out of 212 days). Severe heat stress conditions are recorded for 7 days in July, approaching but not exceeding the medical-emergency threshold.

This report presents a daily analysis of Thom's Discomfort Index (DI) derived from a seasonal WRF forecast driven by CFSv2 boundary conditions. The index combines 2-m air temperature and relative humidity to quantify human thermal discomfort. The formula applied is:

DI = T − (0.55 − 0.0055 × RH) × (T − 14.5)

The forecast period spans the winter-to-summer transition, capturing the full onset of heat stress from spring through peak summer.

DI Threshold Classification

< 21
No discomfort

21–24
<50% affected

24–27
>50% affected

27–29
Most people

29–32
Severe stress

> 32
Medical emergency

52.4%

No discomfort
111 days — Jan, Feb, Mar

8.5%

<50% feel discomfort
18 days — Apr–May

21.7%

>50% feel discomfort
46 days — Apr–Jul

14.2%

Most people discomfort
30 days — Jun–Jul

3.3%

Severe stress
7 days — Jul only

Daily DI — Full Forecast Period

Threshold Onset Dates

DI Threshold	Category	First Exceeded	Value
≥ 21	Less than 50% affected	4 April 2026	21.0
≥ 24	More than 50% affected	23 April 2026	24.8
≥ 27	Most people feel discomfort	6 June 2026	27.1
≥ 29	Severe stress	13 July 2026	29.6
≥ 32	Medical emergency	Not reached during forecast period

Monthly Analysis

January 2026 — Avg: 15.9

Range: 12.5 (30 Jan) – 18.4 (9 Jan)

31 days No discomfort (100%)

February 2026 — Avg: 15.0

Range: 10.3 (23 Feb) – 17.1 (20 Feb)
Period minimum: 10.3 on 23 Feb

28 days No discomfort (100%)

March 2026 — Avg: 15.7

Range: 12.6 (1 Mar) – 20.1 (22 Mar)

31 days No discomfort (100%)

Late-month warming reaches 20.1 — approaching the discomfort threshold.

April 2026 — Avg: 20.2

Range: 15.0 (9 Apr) – 25.1 (24 Apr)

18 No discomfort (60%)
7 <50% affected (23%)
5 >50% affected (17%)

First discomfort day: 4 April

May 2026 — Avg: 23.6

Range: 18.8 (1 May) – 25.0 (31 May)

3 No discomfort (10%)
11 <50% affected (35%)
17 >50% affected (55%)

Discomfort conditions dominate the second half of the month.

June 2026 — Avg: 26.6

Range: 25.0 (3 Jun) – 28.9 (29 Jun)

20 >50% affected (67%)
10 Most people (33%)

First "most people" day: 6 June (27.1)

July 2026 — Avg: 28.4

Range: 26.5 (2 Jul) – 29.6 (13 Jul)
Period maximum: 29.6 on 13 Jul

4 >50% affected (13%)
20 Most people (65%)
7 Severe stress (23%)

Severe stress onset: 13 July (29.6)

Monthly Summary Table

Month	Avg DI	Min	Max	<21	21–24	24–27	27–29	29–32
January	15.9	12.5	18.4	31	—	—	—	—
February	15.0	10.3	17.1	28	—	—	—	—
March	15.7	12.6	20.1	31	—	—	—	—
April	20.2	15.0	25.1	18	7	5	—	—
May	23.6	18.8	25.0	3	11	17	—	—
June	26.6	25.0	28.9	—	—	20	10	—
July	28.4	26.5	29.6	—	—	4	20	7
Total	—	10.3	29.6	111	18	46	30	7

Health Impact Assessment

July Severe Stress Episode (13–14, 20–21, 24, 27–28 July)

Affected days: 7 non-consecutive days above DI 29
Peak value: 29.6 on 13 July
Pattern: Recurring multi-day episodes throughout the second half of July

Risk: Heat exhaustion likely for outdoor workers and elderly. Cooling centres should be activated. Sustained values approaching 30 signal clinical heat stress risk.

June Widespread Discomfort (entire month)

Duration: All 30 days above DI 24 (majority affected)
Days above 27: 10 days (33% of June)
Peak: 28.9 on 29 June

Risk: Persistent thermal stress for the general population. Night-time temperatures may provide insufficient recovery for vulnerable groups.

Population Risk Groups

High-Risk Groups

Elderly (>65): Thermoregulation impairment increases risk at DI > 24
Outdoor workers: Construction, agriculture — acute heat stress risk above DI 27
Infants: High surface-to-volume ratio increases heat absorption
Cardiovascular patients: Heat-induced circulatory strain at DI > 27

Exposure Windows (2026 Forecast)

Population	At-risk period	Days
General public	23 Apr – 31 Jul	101
Majority affected	23 Apr – 31 Jul	83
Most affected	6 Jun – 31 Jul	37
Severe risk	Jul (7 days)	7

Seasonal Progression

Winter–Spring (Jan–Mar): No Discomfort

All 90 days below DI 21 — full comfort range
Coldest day: 10.3 on 23 February
Late-March warming (20.1 on 22 Mar) signals approaching transition

Summer Escalation (Jun–Jul): Critical Period

No comfortable days remain from 1 June onwards
DI rises by ~5 units per month from May to July
Entire July above DI 26.5 — persistent population-wide impact

Recommendations

Spring Preparedness (April–May)

Early Warning Activation — DI ≥ 21 (from 4 April)

Issue public advisories as DI enters the 21–24 range; 18 days in April and 11 in May fall in this bracket
Review outdoor work scheduling — restrict peak-hour labour from late April onwards
Open cooling facilities and shade structures ahead of the summer season

Vulnerable Population Monitoring — DI ≥ 24 (from 23 April)

Activate welfare checks for elderly and isolated individuals
Distribute heat-health guidance to healthcare providers
Ensure hydration stations are operational in public spaces

Summer Response (June–July)

Heat Action Plan — DI ≥ 27 (from 6 June, 37 days total)

Activate the national/regional Heat Action Plan at the start of June
Mandatory rest periods for outdoor workers during 12:00–16:00
Extend hospital emergency capacity; increased ambulance readiness
Public awareness campaigns via media and SMS alerts

Severe Stress Protocol — DI ≥ 29 (7 days in July)

Issue red-level heat alerts for each forecast day above DI 29
Activate cooling centres as emergency shelters
Suspend non-essential outdoor construction and agricultural work
Coordinate with civil protection for real-time monitoring

Alert Level Summary

Green

DI < 21
Normal conditions — standard monitoring

Yellow

DI 21–24
Advisory — hydration and shade guidance

Orange

DI 24–29
Warning — vulnerable population protection

Red

DI ≥ 29
Emergency — cooling centres, work suspension