How to Store Red Wine in Hot Weather: A Guide

Knowing how to store red wine in hot weather is critical for its long-term development and value. According to the Australian Wine Research Institute (AWRI), excessive storage temperatures significantly impact a wine's shelf life, leading to rapid aging and deterioration. Marais (1986) observed faulty flavors and decreased quality in wines stored at 30°C for 12 months. Temperatures above 40°C can induce visual and sensory changes in a matter of days, according to Ough (1986). The AWRI notes that, in general, any storage exceeding 25°C for long periods or 40°C for short periods can affect wine quality. Amon and Simpson (1986) recommend a cool environment between 15-20°C. Maintaining a constant temperature is vital, as thermal cycling can cause cork movement and leakage (Hirlam 2019a,b). Light exposure also poses a risk, producing 'lightstruck' flavors (AWRI). For wines with natural corks, adequate humidity prevents drying out. Experts like Jancis Robinson suggest constant temperatures between 10 and 15°C for optimal storage. High temperatures, such as 35°C, can significantly increase oxygen transfer at the glass-cork interface after nine months. At 50°C, this shift occurs within three months, as found by Chanut et al. (2023).

What are the ideal temperature and humidity for wine storage?

A stable, cool environment is paramount for preserving your wine. Most experts, such as Jancis Robinson, recommend keeping wine at constant temperatures between 10 and 15°C. Tom Stevenson speculates that 11°C may be the most ideal temperature for storage and aging. Karen MacNeil recommends around 13°C for wine intended for aging. Amon and Simpson (1986) advise storing bottled wine in a cool (15-20°C), dry location with the cork in contact with the wine (AWRI, TN09). The lower the temperature, the more slowly a wine develops. The rate of chemical reactions in wine doubles with each 10°C increase in temperature.

Humidity also plays a role, particularly for wines sealed with natural corks. The Comité Champagne recommends high and constant humidity for storing Champagne, between 60% and 80%. While 75% humidity is often cited as ideal that there is very little significant research to definitively establish an optimal range. Climate Controlled Wine Storage facilities typically maintain moderate humidity levels between 55% and 75%. That prevents cork shrinkage and leakage, as well as mold and contamination. Hirlam (2019a,b) advises avoiding thermal cycling, where the temperature varies significantly between day and night (AWRI).

Here is a summary of temperature and humidity recommendations:

Temperature Range	Humidity Range	Notes
15-20°C	Dry	Cool, dry location
10-15°C	n/a	Constant temperature
11°C	n/a	Speculated ideal
13°C	n/a	For aging
10-15°C	60%-80%	Constant temperature, high and constant humidity, for Champagne
n/a	75%	Often cited as ideal, but limited research
n/a	55%-75%	Moderate levels

For more detailed information on optimal conditions, consult our [temperature guide](heat thresholds against our temperature guide).

How does heat damage wine?

Heat can severely compromise the quality and longevity of your wine. The AWRI states that excessive storage temperatures have a marked effect on the shelf life of bottled wine. The result is rapid aging and significant deterioration (TN09). Marais (1986) observed the development of faulty flavors and decreasing overall quality after 12 months’ storage of wine at 30°C. Temperatures in excess of 40°C will induce visual and sensory changes to a wine in only a matter of days (Ough 1986, AWRI, TN09). In general, any storage place where the temperature exceeds 25°C for long periods and 40°C for short periods can affect wine quality (Ough 1992, AWRI, TN09).

Beyond sensory degradation, heat can cause physical damage. Thermal expansion of wine can cause leakage or movement of cork stoppers. It follows exposure to temperatures significantly greater than ambient (AWRI, TN09). Such physical damage does not necessarily imply that the quality of the wine has also been affected. It will affect the appearance and, therefore, the marketability of the wine (AWRI, TN09). Wine exposed to too high a temperature (in excess of 25°C) for long periods may spoil. It can develop off-flavors that taste raisiny or stewed. Temperature swings can also cause adverse chemical reactions. Repeatedly transferring a wine from a warm room to a cool refrigerator is the classic case.

A study by Chanut et al. (2023) looked at microagglomerated cork stoppers. High storage temperatures significantly increase oxygen transfer at the glass-cork interface. The intrinsic oxygen barrier properties of the cork stopper alone remained unchanged over 24 months. Higher temperatures, though, affected the total oxygen transfer for the bottleneck-stopper system. At 35°C, a temperature easily reached during bottle shipping, the picture changed. A significant transfer at the glass-cork interface started beyond nine months of storage. At 50°C, the researchers saw this shift within the first three months of storage (Chanut et al. 2023). Chanut et al. (2023) attribute this increased oxygen transfer to a partial melting of the paraffin and silicon surface treatment on the cork. A modification of the stopper's mechanical properties is the other candidate. Robert Parker (2008) suggests that somewhere between 10 and 25% of wines sold in the USA have been damaged due to exposure to extreme heat (AWRI).

Does bottle orientation matter in hot weather?

The orientation of your wine bottles during storage can be a nuanced decision, with different recommendations depending on the closure and wine type. Amon and Simpson (1986) recommend storing bottled wine with the cork in contact with the wine (AWRI, TN09). Most wine racks are traditionally designed to allow a wine to be stored on its side. The reasoning is that this keeps the cork moist and prevents it from drying out. Research in the late 1990s suggested that storing bottles at a slight angle is ideal. That angle allows partial contact with the wine to keep the cork damp. It also positions the ullage bubble at the top, potentially leading to slower and more gradual oxidation. If a bottle is stored completely on its side, temperature variations could eject wine through the cork, introducing oxygen.

However, not all studies agree on the impact of orientation. Mas et al. (2002) found that after 24 months, wines stored upright had higher yellow/brown color than those stored horizontally, though the differences were not significant. Their study did show higher oxidation for upright samples sealed with agglomerated cork stoppers (AWRI). In contrast, Skouroumounis et al. (2005) tested a wooded Chardonnay and a Riesling. Bottle orientation, horizontal or upright, had little effect on their chemical composition and sensory properties across a 60-month period (AWRI).

For Champagne and other sparkling wines, the advice often differs. These wines tend to age better if kept upright. The internal pressure from trapped carbonic gas provides sufficient humidity and protection from oxygen. However, the Comité Champagne recommends storing Champagne on its side in a cool, dark, draft-free place. They also state that bottles can be stored upright or on their sides. The place should be cool, at a constant temperature of between 10 and 15°C (Comité Champagne).

A recent study by Chanut et al. (2023) specifically investigated microagglomerated corks. It tested two bottle positions. One was vertical, with the cork in contact with the vapor phase; the other horizontal, with the cork in contact with the liquid phase. Neither had a significant influence on oxygen transfer, through the cork itself or at the glass-cork interface, over a 24-month aging period at 20°C. This finding aligns with other studies by Lopes et al. and Hirlam et al. (Chanut et al. 2023).

Wine Type	Recommended Orientation	Primary Reason / Source
Most still wines (natural cork)	Horizontal or slight angle	To keep cork moist and prevent drying out
Champagne and sparkling wines	Upright or on its side	Internal pressure provides humidity; Comité Champagne recommends on its side.
Still wines (microagglomerated cork)	No significant difference (vertical vs. horizontal)	Chanut et al. (2023) found no impact on oxygen transfer over 24 months at 20°C.

For more on fill levels and condition, see our guide on wine ullage levels explained.

What role does light play in wine degradation?

Light exposure is a significant factor in wine degradation. It can cause irreversible damage to a wine's sensory properties. Direct sunlight or incandescent light can adversely react with phenolic compounds in wine. The result is "wine faults". This exposure can affect the taste of a wine through the production of volatile sulfur compounds. That is what is known as ‘lightstruck’ flavour (AWRI). Maujean and Seguin (1983) demonstrated that this flavor is due to the formation of volatile sulfur compounds. Those compounds are believed to derive from sulfur-containing amino acids like methionine and cysteine (AWRI, TN09). Riboflavin (vitamin B2) is present in low levels in musts and wines. It undergoes photo-activation when exposed to light at wavelengths of 370 nm and 440 nm, which initiates these reactions (AWRI, TN09).

Light-bodied white wines are particularly vulnerable to light exposure. They are often packaged in tinted wine bottles for some protection. Wines in clear, light green, and blue colored bottles are the most susceptible. They may require extra precautions for storage. Dozon and Noble (1989) found that still white wines bottled in green glass developed a statistically significant lightstruck flavor after 31.1 hours of exposure to fluorescent lamps. The same wines in clear glass developed the off-flavor after only 3.3 hours (AWRI, TN09).

The intensity of light sources also matters. Gordon Watson, cited by the AWRI (TN09), notes that direct sunlight provides 4286 times the amount of UV-A radiation as a 36W fluorescent lamp. Sunlight reaches bottled wine in retail window displays. That exposure is likely more deleterious to wine quality than exposure to electric lighting systems (AWRI, TN09). To mitigate this, store cellar wines in corrugated boxes or wooden crates. Amber glass is the most effective in excluding wavelengths below about 450 nm (Rankine 1989, AWRI, TN09). The Comité Champagne also explicitly recommends protecting bottles from light (Comité Champagne). Furthermore, light exposure can exacerbate copper instability in susceptible white wines. The AWRI (TN09) recommends protection from light above roughly 0.5 mg/L of copper.

How do different closures perform under heat?

The choice of closure interacts with temperature. Together they significantly impact a wine's aging potential, particularly in warm conditions. A study by Chanut et al. (2023) specifically investigated microagglomerated cork stoppers of the Diam 5 type. A paraffin and silicone surface treatment coated them. That research showed how these closures perform under varying temperatures and conditions.

The study ran over a long storage period of 24 months. Storage conditions did not modify the intrinsic oxygen diffusion coefficient of the cork stopper alone. Those conditions included temperature, storage position, and the presence of model wine (Chanut et al. 2023). This suggests the cork material itself is stable. However, the presence of model wine and, crucially, temperature significantly influenced the total oxygen transfer. That total includes both the transfer through the stopper and the transfer at the glass-cork interface.

At 20°C, the total diffusion coefficient for the bottleneck-stopper system increased after the initial three months of storage. It went from 2.3 × 10−11 to 4.7 × 10−11 m2 s−1. In that scenario, the glass-cork interface carried nearly 70% of the total oxygen transfer (Chanut et al. 2023). The impact of higher temperatures was even more pronounced. At 35°C, a temperature commonly reached during bottle shipping, the total oxygen transfer held. It did not increase significantly for up to nine months. Beyond this duration, however, a significant transfer at the glass-cork interface began to occur. At 50°C, the researchers saw this shift in oxygen transfer much earlier, within the first three months of storage (Chanut et al. 2023). Chanut et al. (2023) attribute this increased oxygen transfer at higher temperatures to a partial melting of the paraffin and silicon surface treatment agent on the cork. A modification of the stopper's mechanical properties is the other candidate.

The study focused on a specific type of microagglomerated cork. For alternative wine closures, such as screw caps or synthetic stoppers, concerns about humidity and oxidation may be less pronounced. However, these closures became popular relatively recently. There have been fewer opportunities for extensive research into their long-term storage and aging potential than for natural corks. Understanding these dynamics is crucial for protecting your fine wine investment.

What are the signs of heat damage?

Identifying heat damage in your wine collection is crucial. It drives your assessment of quality and potential resale value. The Australian Wine Research Institute (AWRI) outlines several methods for assessing whether a wine has experienced heat damage. They combine chemical, physical, and sensory tests.

According to the AWRI, you should look visually for signs of leakage, closure damage, wine travel or seepage on corks, increased ullage, and label damage. An increased ullage, or fill level, is a strong indicator. It points to thermal expansion and subsequent wine loss.

According to the AWRI, chemical analysis for white wines typically includes measuring color development, specifically yellow/brown color (measured by OD420). It also covers free and total SO2 levels. These SO2 levels are then compared to levels at bottling and expected loss rates under ideal conditions. For red wines, chemical analysis involves spectral measurements for color and phenolics, as well as free and total SO2 levels (AWRI).

Sensory analysis is also a key component. Wines exposed to extreme temperatures tend to lose their fresh fruity characters. They show more developed fruit characteristics instead. At extreme levels of temperature exposure, oxidized and cooked characteristics can be observed (AWRI). We also note the effect of too high a temperature, in excess of 25°C, over long periods. The wine may develop off-flavors that taste raisiny or stewed. If you suspect heat damage, compare the affected wine to unaffected samples of the same wine. Hold-back stock is the obvious source. That comparison can greatly assist in understanding the extent and nature of the damage, according to the AWRI. This can help you determine if a wine is still suitable for consumption or if it has passed its drinking window.

Access our drink-window data for your cellar to make informed decisions about your collection.