UK Garden Weather Forecast by Postcode

Frost risk depends on more than tonight's forecast low — clear skies and calm wind let heat escape fast, while cloud and breeze hold it in. Enter your postcode below for a 5-day forecast plus an estimated frost risk for tonight, built from Met Office data. This is a helpful estimate, not an official Met Office warning — always check the Met Office directly for official warnings.

How We Estimate Frost Risk

Our Estimated Frost Risk is calculated from four things the Met Office forecast gives us: tonight's forecast minimum temperature, humidity (used to estimate dew point), wind speed and cloud cover. Clear, calm nights lose heat to the sky fastest — that is classic radiation-frost weather — while cloud cover and breeze both work against a hard frost forming, even on a cold night. We combine these into a category (None, Low, Moderate or High) and deliberately round up when the inputs are borderline, because the cost of an unprotected frost-damaged plant is higher than the cost of an unnecessary fleece.

This is an algorithmic estimate for everyday gardening decisions, not an official Met Office frost warning. For official Met Office warnings, check their own severe weather page directly.

Soil temperature: an honest estimate, not a rolling mean

You may see other sites quote a “7-day rolling mean” for soil temperature. We don't, because the Met Office daily forecast feed we use returns about a week ahead and at most one day back — the DataHub daily time step is documented as seven days, one past and six future — not seven days of history, so a genuine 7-day mean isn't something this data source actually supports.¹ Instead we show a short-window estimate, built from the average air temperature across the next three forecast days, starting today, less one degree to allow for the lag between air and soil, and we label it plainly: an estimate, not a soil sensor reading. For anything precision-dependent — like deciding whether to sow grass seed, where the RHS gives a minimum soil temperature of 7°C² — a cheap soil thermometer pushed 50mm into the ground beats any forecast-based estimate.

Frequently Asked Questions

Sources and checking notes

Checked by Gary Hodson on 15 September 2026. The forecast data comes from the Met Office Weather DataHub. The frost-risk category and the soil-temperature estimate are GardenCalc's own methods, described above, and are not Met Office products.

1. Met Office Weather DataHub — Global Spot overview, in the site-specific forecast documentation. datahub.metoffice.gov.uk/docs/f/category/site-specific/overview. Checked 15 September 2026: “Daily: 7 days (one day past, six days future).” That time step is documented for the Global Spot product; the UK site-specific daily point feed this page calls returned today plus six forecast days when we checked it the same day, and our code discards any past-day entry before scoring.
2. Royal Horticultural Society — Monthly gardening tips: October, lawns. rhs.org.uk/advice/in-month/october/lawns. Checked 15 September 2026: “for good germination, soil temperature should be at least 7°C.”