Lee State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lee State Park clear sky chart from 2005-11-06 to 2025-12-18.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	12% 6% 2 6% 4 4 4 4 6% 8% 43%	127154
	Night	13% 6% 2 6% 4 4 4 4 5% 8% 44%	123886
Transparency	Day	37% 8% 13% 19% 18% 6%	130774
	Night	37% 7% 11% 17% 20% 7%	128322
Seeing	Day	14% 7% 22% 25% 21% 12%	16956
	Night	15% 6% 23% 33% 20% 3	27043

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 5% 2 4 3 2 3 2 4 6% 55%	4056
	11th to 20th	Day	12% 5% 2 4 3 3 3 2 3 5% 58%	4060
	21st to end	Day	14% 8% 3 7% 4 4 4 3 5% 5% 44%	4466
February	1st to 10th	Day	15% 8% 2 6% 4 3 4 4 5% 7% 42%	1800
	11th to 20th	Day	20% 6% 2 6% 4 3 3 2 5% 5% 44%	1887
	21st to end	Day	17% 6% 2 6% 4 4 4 3 5% 6% 43%	1767
March	1st to 10th	Day	19% 8% 3 7% 4 4 4 3 4 5% 39%	4935
	11th to 20th	Day	9% 4 2 5% 4 4 3 3 5% 7% 54%	4980
	21st to end	Day	13% 6% 3 6% 4 4 4 3 4 5% 48%	5465
April	1st to 10th	Day	9% 4 2 5% 4 5% 5% 4 6% 8% 50%	2229
	11th to 20th	Day	10% 5% 2 5% 3 5% 4 4 5% 8% 51%	2374
	21st to end	Day	8% 5% 2 5% 4 4 4 4 5% 7% 52%	2437
May	1st to 10th	Day	8% 7% 2 7% 5% 5% 5% 4 7% 11% 39%	5862
	11th to 20th	Day	17% 8% 2 6% 5% 4 5% 5% 7% 9% 32%	5861
	21st to end	Day	10% 5% 2 5% 4 4 5% 4 7% 9% 44%	6433
June	1st to 10th	Day	9% 7% 2 6% 6% 5% 5% 6% 9% 10% 36%	2600
	11th to 20th	Day	7% 4 2 6% 4 6% 5% 6% 9% 11% 41%	2600
	21st to end	Day	6% 4 2 7% 6% 6% 6% 5% 8% 12% 40%	2600
July	1st to 10th	Day	11% 7% 2 9% 6% 6% 7% 6% 8% 10% 28%	5900
	11th to 20th	Day	6% 5% 2 6% 5% 6% 6% 6% 10% 15% 33%	5900
	21st to end	Day	9% 6% 3 8% 6% 6% 6% 5% 9% 13% 29%	6424
August	1st to 10th	Day	23% 7% 3 7% 5% 5% 6% 5% 8% 10% 20%	4234
	11th to 20th	Day	11% 6% 2 6% 5% 5% 6% 4 8% 11% 36%	4119
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 7% 11% 46%	4312
September	1st to 10th	Day	7% 4 2 7% 5% 5% 5% 5% 7% 9% 43%	2293
	11th to 20th	Day	12% 7% 2 6% 5% 5% 5% 4 6% 8% 42%	2200
	21st to end	Day	16% 7% 3 6% 4 4 3 3 6% 7% 41%	2200
October	1st to 10th	Day	12% 6% 2 6% 3 4 4 3 5% 6% 49%	2038
	11th to 20th	Day	10% 5% 2 5% 3 3 4 2 4 6% 58%	2000
	21st to end	Day	11% 5% 2 5% 3 3 3 2 4 6% 58%	2200
November	1st to 10th	Day	12% 5% 2 4 3 3 3 3 5% 5% 55%	2057
	11th to 20th	Day	14% 6% 2 5% 3 2 3 3 4 6% 53%	2053
	21st to end	Day	12% 6% 2 6% 3 3 3 3 5% 6% 51%	1890
December	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 4 5% 52%	3020
	11th to 20th	Day	15% 5% 2 5% 4 3 4 3 5% 6% 48%	3436
	21st to end	Day	19% 7% 3 6% 3 3 4 3 4 6% 45%	4466
January	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 4 5% 57%	5889
	11th to 20th	Night	12% 6% 2 5% 4 4 4 3 4 6% 51%	5900
	21st to end	Night	13% 9% 3 6% 4 3 3 3 4 6% 46%	6490
February	1st to 10th	Night	15% 6% 2 6% 4 4 4 4 5% 7% 44%	2600
	11th to 20th	Night	19% 6% 2 6% 4 4 4 3 4 5% 42%	2396
	21st to end	Night	13% 6% 2 7% 4 3 4 3 5% 7% 45%	1861
March	1st to 10th	Night	19% 8% 3 6% 4 3 4 3 4 6% 40%	4918
	11th to 20th	Night	10% 4 2 5% 3 3 4 3 5% 8% 54%	4980
	21st to end	Night	14% 4 2 5% 4 4 4 4 4 7% 50%	5467
April	1st to 10th	Night	11% 7% 2 4 3 4 4 3 5% 7% 49%	2170
	11th to 20th	Night	10% 4 2 5% 4 3 3 3 4 7% 54%	1975
	21st to end	Night	8% 4 2 6% 4 4 4 4 6% 8% 51%	1978
May	1st to 10th	Night	9% 6% 2 6% 4 5% 5% 4 7% 9% 42%	4033
	11th to 20th	Night	17% 6% 3 6% 4 4 4 4 6% 9% 35%	4032
	21st to end	Night	12% 5% 2 6% 4 4 5% 5% 6% 9% 41%	4421
June	1st to 10th	Night	10% 7% 3 5% 5% 4 6% 5% 10% 9% 36%	1800
	11th to 20th	Night	8% 6% 2 6% 6% 6% 6% 5% 8% 11% 37%	1800
	21st to end	Night	6% 5% 2 5% 5% 5% 6% 7% 12% 12% 35%	1800
July	1st to 10th	Night	13% 7% 3 9% 6% 6% 7% 6% 7% 10% 25%	4058
	11th to 20th	Night	8% 6% 3 8% 6% 6% 7% 6% 10% 13% 27%	4057
	21st to end	Night	12% 8% 4 10% 6% 6% 7% 6% 8% 10% 23%	4427
August	1st to 10th	Night	23% 7% 2 8% 5% 6% 5% 5% 6% 9% 22%	2915
	11th to 20th	Night	12% 6% 2 7% 5% 6% 5% 5% 7% 10% 34%	2894
	21st to end	Night	6% 4 2 5% 4 3 5% 4 8% 12% 48%	3586
September	1st to 10th	Night	8% 5% 2 6% 5% 5% 6% 5% 7% 10% 40%	2102
	11th to 20th	Night	11% 8% 3 9% 5% 4 4 4 5% 6% 40%	2200
	21st to end	Night	17% 6% 3 7% 4 4 5% 3 4 6% 42%	2200
October	1st to 10th	Night	12% 6% 2 5% 3 4 4 3 5% 7% 50%	2360
	11th to 20th	Night	13% 4 2 4 3 3 3 3 4 5% 56%	2400
	21st to end	Night	10% 5% 2 4 3 3 2 3 5% 6% 57%	2640
November	1st to 10th	Night	12% 5% 2 4 4 4 3 2 3 6% 55%	2461
	11th to 20th	Night	13% 7% 2 3 3 3 2 3 5% 7% 52%	2562
	21st to end	Night	12% 5% 2 5% 4 4 3 3 5% 7% 50%	2730
December	1st to 10th	Night	13% 6% 2 5% 3 3 2 3 4 5% 53%	4380
	11th to 20th	Night	15% 7% 2 6% 4 4 4 3 4 5% 45%	4914
	21st to end	Night	19% 6% 2 6% 3 3 3 3 4 6% 44%	6490

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	31% 4 5% 19% 33% 7%	4057
	11th to 20th	Day	30% 4 5% 16% 36% 9%	4060
	21st to end	Day	42% 4 5% 16% 22% 11%	4466
February	1st to 10th	Day	41% 6% 11% 19% 19% 5%	1800
	11th to 20th	Day	43% 5% 6% 18% 23% 6%	1897
	21st to end	Day	42% 5% 9% 15% 21% 9%	1767
March	1st to 10th	Day	47% 5% 6% 12% 20% 10%	4935
	11th to 20th	Day	29% 5% 8% 15% 26% 16%	4980
	21st to end	Day	38% 5% 8% 19% 21% 9%	5465
April	1st to 10th	Day	30% 6% 12% 19% 26% 6%	2229
	11th to 20th	Day	31% 6% 11% 22% 21% 10%	2374
	21st to end	Day	30% 7% 12% 26% 21% 4	2437
May	1st to 10th	Day	38% 9% 17% 25% 11% 1	5897
	11th to 20th	Day	46% 8% 15% 19% 11%	5865
	21st to end	Day	34% 10% 15% 20% 19% 3	6447
June	1st to 10th	Day	37% 11% 18% 23% 10% 1	2600
	11th to 20th	Day	32% 11% 20% 23% 13% 1	2600
	21st to end	Day	34% 10% 20% 23% 11% 1	2600
July	1st to 10th	Day	46% 12% 17% 19% 5% 1	5835
	11th to 20th	Day	36% 15% 35% 11% 3 1	5831
	21st to end	Day	43% 13% 17% 19% 7%	6240
August	1st to 10th	Day	55% 12% 18% 11% 4	4221
	11th to 20th	Day	39% 11% 17% 20% 13%	4158
	21st to end	Day	30% 9% 14% 32% 13% 1	4312
September	1st to 10th	Day	34% 12% 15% 18% 17% 4	2293
	11th to 20th	Day	40% 8% 11% 17% 20% 4	2200
	21st to end	Day	41% 7% 10% 21% 15% 5%	2200
October	1st to 10th	Day	33% 5% 7% 20% 27% 7%	3311
	11th to 20th	Day	19% 3 5% 17% 28% 27%	3240
	21st to end	Day	26% 3 5% 20% 29% 17%	3538
November	1st to 10th	Day	31% 4 7% 19% 27% 11%	2057
	11th to 20th	Day	33% 5% 7% 18% 27% 10%	2053
	21st to end	Day	34% 4 9% 20% 24% 9%	1890
December	1st to 10th	Day	36% 4 7% 16% 27% 10%	3020
	11th to 20th	Day	37% 4 12% 21% 20% 6%	3433
	21st to end	Day	41% 4 8% 21% 23% 2	4466
January	1st to 10th	Night	30% 4 6% 17% 36% 7%	5889
	11th to 20th	Night	34% 5% 6% 15% 33% 7%	5900
	21st to end	Night	40% 5% 4 13% 28% 9%	6490
February	1st to 10th	Night	40% 5% 8% 20% 19% 8%	2600
	11th to 20th	Night	44% 5% 7% 16% 21% 8%	2397
	21st to end	Night	38% 5% 9% 17% 20% 11%	1861
March	1st to 10th	Night	45% 6% 7% 11% 23% 9%	4918
	11th to 20th	Night	28% 5% 8% 12% 28% 19%	4980
	21st to end	Night	34% 5% 8% 21% 21% 11%	5467
April	1st to 10th	Night	34% 6% 11% 19% 20% 10%	2170
	11th to 20th	Night	30% 6% 10% 20% 22% 12%	1975
	21st to end	Night	30% 7% 13% 24% 21% 5%	1978
May	1st to 10th	Night	35% 10% 16% 23% 15% 2	4060
	11th to 20th	Night	43% 9% 19% 17% 11%	4033
	21st to end	Night	34% 11% 14% 22% 17% 2	4429
June	1st to 10th	Night	38% 13% 16% 22% 10% 2	1800
	11th to 20th	Night	37% 11% 20% 19% 11% 2	1800
	21st to end	Night	32% 14% 22% 21% 10% 2	1800
July	1st to 10th	Night	50% 13% 19% 13% 4 1	4015
	11th to 20th	Night	43% 17% 28% 8% 3	4006
	21st to end	Night	53% 11% 15% 16% 4	4297
August	1st to 10th	Night	55% 10% 19% 13% 2 1	2904
	11th to 20th	Night	43% 11% 20% 20% 6%	2921
	21st to end	Night	28% 8% 15% 33% 15% 1	3586
September	1st to 10th	Night	36% 12% 14% 19% 14% 5%	2102
	11th to 20th	Night	44% 8% 11% 18% 16% 3	2200
	21st to end	Night	43% 8% 12% 18% 15% 4	2200
October	1st to 10th	Night	34% 6% 9% 19% 26% 7%	3854
	11th to 20th	Night	20% 3 6% 15% 26% 30%	3899
	21st to end	Night	25% 5% 6% 20% 27% 17%	4252
November	1st to 10th	Night	32% 4 8% 15% 27% 14%	2461
	11th to 20th	Night	33% 5% 7% 15% 28% 12%	2562
	21st to end	Night	34% 4 9% 20% 23% 10%	2730
December	1st to 10th	Night	34% 4 7% 15% 28% 11%	4380
	11th to 20th	Night	42% 5% 10% 17% 18% 9%	4916
	21st to end	Night	42% 4 8% 20% 23% 3	6490

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	18% 12% 44% 22% 4	300
	11th to 20th	Day	15% 14% 40% 23% 8%	300
	21st to end	Day	21% 17% 36% 20% 6%	330
February	1st to 10th	Day	17% 13% 38% 26% 6%	300
	11th to 20th	Day	30% 12% 39% 17% 2	300
	21st to end	Day	19% 14% 37% 22% 7% 1	366
March	1st to 10th	Day	17% 15% 30% 26% 11%	500
	11th to 20th	Day	15% 12% 42% 23% 7% 1	500
	21st to end	Day	15% 14% 36% 23% 11% 1	550
April	1st to 10th	Day	13% 14% 33% 24% 14% 1	500
	11th to 20th	Day	11% 9% 28% 27% 19% 7%	492
	21st to end	Day	10% 6% 25% 28% 23% 8%	500
May	1st to 10th	Day	9% 10% 28% 28% 18% 7%	503
	11th to 20th	Day	15% 4 17% 28% 23% 13%	527
	21st to end	Day	13% 5% 14% 23% 23% 22%	573
June	1st to 10th	Day	11% 3 12% 29% 29% 16%	530
	11th to 20th	Day	9% 2 13% 26% 28% 22%	530
	21st to end	Day	7% 1 8% 28% 31% 25%	530
July	1st to 10th	Day	10% 2 5% 20% 31% 32%	525
	11th to 20th	Day	8% 2 5% 18% 34% 33%	524
	21st to end	Day	5% 2 5% 23% 40% 25%	576
August	1st to 10th	Day	19% 2 7% 22% 28% 22%	526
	11th to 20th	Day	12% 3 5% 21% 30% 29%	519
	21st to end	Day	13% 2 10% 21% 30% 25%	583
September	1st to 10th	Day	9% 3 9% 27% 33% 21%	530
	11th to 20th	Day	15% 3 13% 22% 30% 16%	530
	21st to end	Day	19% 2 11% 28% 29% 11%	530
October	1st to 10th	Day	14% 3 20% 28% 24% 11%	530
	11th to 20th	Day	11% 5% 22% 28% 26% 8%	530
	21st to end	Day	13% 5% 25% 27% 22% 8%	583
November	1st to 10th	Day	16% 5% 24% 31% 18% 6%	535
	11th to 20th	Day	17% 7% 33% 27% 14% 1	493
	21st to end	Day	10% 8% 37% 27% 15% 3	330
December	1st to 10th	Day	23% 10% 35% 23% 8% 1	330
	11th to 20th	Day	18% 10% 31% 26% 14% 2	321
	21st to end	Day	22% 12% 35% 19% 10% 2	330
January	1st to 10th	Night	17% 11% 36% 27% 8% 1	800
	11th to 20th	Night	17% 11% 33% 33% 7%	800
	21st to end	Night	19% 8% 39% 32% 2	880
February	1st to 10th	Night	18% 9% 34% 33% 6%	800
	11th to 20th	Night	22% 11% 37% 29% 2	783
	21st to end	Night	16% 13% 35% 30% 6%	660
March	1st to 10th	Night	18% 10% 32% 32% 7%	800
	11th to 20th	Night	16% 10% 35% 31% 8%	800
	21st to end	Night	15% 9% 38% 31% 8%	880
April	1st to 10th	Night	14% 14% 35% 29% 9%	800
	11th to 20th	Night	12% 10% 31% 34% 14% 1	791
	21st to end	Night	9% 8% 28% 41% 13%	778
May	1st to 10th	Night	11% 5% 29% 40% 14%	600
	11th to 20th	Night	13% 5% 24% 39% 17% 2	591
	21st to end	Night	10% 2 12% 38% 34% 3	650
June	1st to 10th	Night	13% 3 12% 42% 28% 3	600
	11th to 20th	Night	10% 2 11% 38% 30% 9%	600
	21st to end	Night	7% 2 10% 38% 35% 8%	600
July	1st to 10th	Night	9% 2 8% 31% 44% 6%	585
	11th to 20th	Night	10% 1 5% 27% 49% 8%	582
	21st to end	Night	7% 3 5% 34% 45% 7%	657
August	1st to 10th	Night	15% 2 7% 26% 44% 7%	597
	11th to 20th	Night	14% 2 5% 32% 40% 7%	600
	21st to end	Night	13% 2 7% 31% 42% 6%	880
September	1st to 10th	Night	10% 2 9% 32% 41% 6%	800
	11th to 20th	Night	15% 3 8% 34% 35% 5%	800
	21st to end	Night	20% 2 13% 34% 29% 3	800
October	1st to 10th	Night	14% 3 18% 32% 29% 4	800
	11th to 20th	Night	14% 6% 20% 34% 25% 2	800
	21st to end	Night	12% 5% 24% 34% 22% 2	880
November	1st to 10th	Night	13% 5% 23% 36% 18% 4	820
	11th to 20th	Night	18% 7% 28% 34% 12% 1	840
	21st to end	Night	14% 6% 30% 32% 16% 1	840
December	1st to 10th	Night	21% 9% 26% 34% 9% 1	840
	11th to 20th	Night	17% 7% 27% 36% 12% 1	829
	21st to end	Night	25% 9% 24% 32% 9% 1	880

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