select pnm,lnm,st_cd,st_nm,cnty_id,dm,dm_date,dm_hist,avg_tmax_data,avg_tmin_data,avg_prcp_data,rec_hi_data,rec_lo_data,avg_sndp_data,x,y,ff,lf,fd,hz,er,hz_source,kg,hzd,clim_stn_nm,hz12,hz90, feels_like_min,feels_like_max,days_of_prcp,snow,cloud_cover,humidity,wind_speed from worldtg8_pm.pm_climate_points_namer where surl = 'winthrop-harbor' and st_surl='illinois' and iso_cc = 'US' and prim_loc in (1,2) Winthrop Harbor Illinois Climate Data - Updated February 2026

Winthrop Harbor Illinois Climate Data

Monthly Average Climate Data for Winthrop Harbor Illinois

Switch Data to Celsius/Metric Units

Month	Avg. Low	Avg. High	Avg. Precip
January	16.2 °F	30.2 °F	1.94 in.
February	18.9 °F	33.2 °F	1.89 in.
March	27.8 °F	42.5 °F	2.3 in.
April	37.6 °F	52.8 °F	3.96 in.
May	47.4 °F	63.8 °F	4.23 in.
June	57.6 °F	73.8 °F	4.11 in.
July	64.3 °F	79.7 °F	3.49 in.
August	63.7 °F	78.6 °F	3.54 in.
September	56.0 °F	72.1 °F	3.42 in.
October	44.2 °F	60.2 °F	3.19 in.
November	32.6 °F	47.2 °F	2.38 in.
December	22.3 °F	35.7 °F	2.07 in.
Annual	40.7 °F	55.8 °F	36.52 in.

Climate Data for Winthrop Harbor Illinois

Average First Frost Date	Oct. 21 - Oct. 31
Average Last Frost Date	Apr. 21 - Apr. 30
Average Days With Frost	75-100 Days
Plant Hardiness Zone	Zone 6a : -10°F to -5°F
Plant Hardiness Zone - 2012	Zone 5b : -15°F to -10°F
Current Drought Conditions	Abnormally Dry
Köppen Climate Classification	Dfa - Humid Continental Hot Summers With Year Around Precipitation

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