Record-breaking July warmth could affect parts of NSW this weekend before a strong cold front sweeps over the state. A stubborn high pressure system lingering over eastern Australia this week will allow warm air to flow over NSW from the northwest. Only relatively weak fronts are going to affect the state during the working week, allowing this pattern to remain in place until a stronger cold front arrives in most parts of the state on Sunday. Maximum temperatures are forecast to be near or above average for July across most of state between now and Friday. The week of warm winter days will culminate in what could be the highest July temperatures on record in some areas this weekend. Western NSW could give 30 degrees a nudge on the weekend as the warmest air arrives ahead of the stronger front. Tibooburra is forecast to reach 29 degrees on Saturday and nearby Bourke 28 degrees. This is within a degree of Bourke's highest July temperature in 146 years of records, which currently stands at 28.9 degrees from 1990. Sydney is forecast to reach 22 degrees on Friday and Saturday and 25 degrees on Sunday. The city's highest July temperature during the last 158 years of records was 25.9 degrees, also from 1990. Grafton in the state's northeast should comfortably climb into the mid-twenties on the weekend and could challenge its July record of 28.2 degrees from 1970. Sunday is the best chance, with a forecast top of 27 degrees. The winter warmth will be flushed out of NSW as the strong cold front sweeps through the state between Saturday night and Monday. This blustery change will most likely reach the far west on Saturday night, move across central and southern districts on Sunday and arrive in the northeast on Monday.