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 2024-11-11.

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% 42%	101224
	Night	13% 6% 2 6% 4 4 4 4 6% 8% 43%	97899
Transparency	Day	37% 8% 12% 19% 18% 6%	104888
	Night	37% 8% 11% 18% 18% 7%	102361
Seeing	Day	14% 6% 21% 24% 22% 12%	15474
	Night	15% 6% 23% 33% 21% 3	25549

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	15% 5% 2 5% 4 2 3 3 5% 7% 48%	2836
	11th to 20th	Day	12% 6% 2 4 4 3 4 3 3 7% 53%	2840
	21st to end	Day	16% 9% 3 6% 4 4 3 3 4 4 43%	3124
February	1st to 10th	Day	16% 8% 2 6% 4 3 4 4 5% 7% 42%	1710
	11th to 20th	Day	19% 6% 2 6% 4 3 3 2 5% 5% 45%	1790
	21st to end	Day	18% 6% 2 6% 4 4 4 3 5% 6% 42%	1681
March	1st to 10th	Day	20% 10% 3 8% 4 3 3 3 4 5% 36%	3435
	11th to 20th	Day	9% 4 2 5% 4 4 3 3 6% 7% 54%	3480
	21st to end	Day	17% 7% 3 6% 4 3 3 3 4 6% 44%	3815
April	1st to 10th	Day	9% 4 2 5% 4 5% 5% 4 6% 7% 50%	2117
	11th to 20th	Day	10% 5% 2 5% 3 5% 4 4 5% 8% 49%	2254
	21st to end	Day	9% 5% 2 5% 3 4 4 4 4 7% 53%	2315
May	1st to 10th	Day	8% 7% 3 7% 5% 5% 4 5% 7% 10% 40%	4082
	11th to 20th	Day	15% 8% 3 7% 4 4 4 4 6% 8% 38%	4081
	21st to end	Day	6% 4 2 5% 4 5% 5% 4 8% 11% 47%	4476
June	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 6% 10% 10% 36%	2470
	11th to 20th	Day	7% 4 2 6% 4 6% 5% 6% 9% 11% 41%	2470
	21st to end	Day	6% 4 2 7% 6% 6% 6% 5% 8% 11% 38%	2470
July	1st to 10th	Day	11% 6% 2 8% 5% 6% 7% 6% 8% 11% 30%	4120
	11th to 20th	Day	7% 6% 2 6% 5% 6% 6% 6% 10% 14% 32%	4120
	21st to end	Day	10% 7% 3 8% 7% 6% 7% 6% 9% 13% 25%	4466
August	1st to 10th	Day	23% 7% 3 7% 5% 5% 6% 5% 8% 10% 21%	4104
	11th to 20th	Day	10% 6% 2 6% 5% 5% 6% 4 8% 11% 36%	3991
	21st to end	Day	6% 4 2 5% 4 4 5% 5% 7% 11% 47%	4180
September	1st to 10th	Day	8% 5% 2 7% 6% 5% 5% 5% 7% 9% 42%	2179
	11th to 20th	Day	13% 7% 2 6% 5% 5% 4 4 5% 8% 41%	2090
	21st to end	Day	15% 7% 3 6% 4 4 3 4 6% 7% 41%	2090
October	1st to 10th	Day	13% 6% 2 6% 3 3 4 2 4 6% 50%	1936
	11th to 20th	Day	9% 5% 2 5% 3 3 4 2 4 6% 58%	1900
	21st to end	Day	10% 5% 2 5% 3 3 3 2 4 6% 58%	2090
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 5% 5% 54%	1957
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 4 6% 51%	1858
	21st to end	Day	14% 6% 2 6% 3 3 4 3 5% 6% 50%	1710
December	1st to 10th	Day	15% 9% 3 7% 4 5% 4 3 5% 6% 39%	1710
	11th to 20th	Day	15% 5% 1 4 3 3 3 2 4 6% 53%	2153
	21st to end	Day	18% 7% 3 6% 3 3 4 3 4 6% 44%	3124
January	1st to 10th	Night	15% 6% 2 6% 3 3 3 4 4 5% 48%	4109
	11th to 20th	Night	10% 7% 2 7% 5% 4 5% 4 5% 7% 44%	4120
	21st to end	Night	16% 8% 3 6% 4 4 4 3 4 5% 44%	4532
February	1st to 10th	Night	16% 6% 2 6% 3 4 4 4 5% 7% 43%	2470
	11th to 20th	Night	18% 6% 2 6% 4 4 4 3 4 5% 43%	2274
	21st to end	Night	14% 6% 2 7% 4 4 4 3 5% 7% 44%	1771
March	1st to 10th	Night	23% 10% 3 7% 5% 3 3 3 4 6% 33%	3418
	11th to 20th	Night	11% 5% 2 5% 4 4 4 3 5% 7% 49%	3480
	21st to end	Night	17% 4 2 5% 4 4 4 4 5% 8% 44%	3817
April	1st to 10th	Night	11% 6% 2 4 3 4 4 3 5% 7% 50%	2062
	11th to 20th	Night	10% 4 2 5% 4 4 4 3 4 7% 52%	1875
	21st to end	Night	8% 4 2 6% 4 3 4 4 6% 8% 51%	1879
May	1st to 10th	Night	9% 7% 2 5% 4 5% 5% 4 7% 9% 43%	2813
	11th to 20th	Night	14% 7% 3 7% 4 4 3 4 6% 9% 39%	2812
	21st to end	Night	7% 4 2 6% 5% 4 5% 5% 6% 9% 45%	3079
June	1st to 10th	Night	10% 7% 3 5% 5% 4 6% 6% 10% 9% 36%	1710
	11th to 20th	Night	9% 6% 2 6% 6% 6% 6% 4 8% 12% 37%	1710
	21st to end	Night	6% 6% 2 6% 5% 5% 5% 7% 11% 12% 34%	1710
July	1st to 10th	Night	12% 7% 3 8% 6% 6% 6% 6% 7% 10% 29%	2840
	11th to 20th	Night	10% 7% 3 7% 6% 6% 7% 5% 9% 11% 29%	2840
	21st to end	Night	13% 8% 4 10% 6% 6% 7% 5% 9% 9% 23%	3087
August	1st to 10th	Night	23% 7% 2 8% 5% 6% 5% 5% 7% 9% 23%	2825
	11th to 20th	Night	12% 6% 2 7% 5% 6% 5% 5% 7% 10% 34%	2803
	21st to end	Night	6% 4 2 4 4 3 5% 4 8% 12% 48%	3476
September	1st to 10th	Night	9% 5% 2 6% 5% 5% 6% 5% 7% 10% 40%	1997
	11th to 20th	Night	12% 8% 3 9% 6% 4 4 4 5% 6% 39%	2090
	21st to end	Night	17% 6% 3 7% 4 4 5% 3 4 5% 42%	2090
October	1st to 10th	Night	13% 6% 2 4 3 3 4 3 5% 7% 51%	2242
	11th to 20th	Night	12% 4 2 4 3 3 3 3 4 5% 56%	2280
	21st to end	Night	9% 5% 2 5% 3 4 2 3 5% 6% 57%	2508
November	1st to 10th	Night	12% 5% 2 5% 4 4 3 3 3 6% 54%	2341
	11th to 20th	Night	14% 7% 2 3 4 3 2 3 5% 7% 51%	2325
	21st to end	Night	13% 5% 2 4 4 4 3 3 5% 6% 49%	2470
December	1st to 10th	Night	17% 7% 3 6% 4 4 3 3 5% 6% 43%	2470
	11th to 20th	Night	16% 6% 1 4 3 3 3 2 4 4 52%	3042
	21st to end	Night	19% 6% 3 5% 3 4 4 3 5% 7% 42%	4532

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	34% 6% 7% 24% 23% 7%	2837
	11th to 20th	Day	32% 5% 6% 19% 28% 10%	2840
	21st to end	Day	44% 4 5% 16% 22% 9%	3124
February	1st to 10th	Day	42% 6% 10% 18% 19% 5%	1710
	11th to 20th	Day	42% 5% 6% 18% 23% 6%	1800
	21st to end	Day	43% 5% 9% 14% 20% 8%	1681
March	1st to 10th	Day	49% 6% 8% 14% 14% 9%	3435
	11th to 20th	Day	29% 6% 9% 17% 28% 11%	3480
	21st to end	Day	41% 5% 8% 19% 21% 5%	3815
April	1st to 10th	Day	31% 7% 12% 18% 27% 6%	2117
	11th to 20th	Day	32% 6% 11% 20% 20% 11%	2254
	21st to end	Day	30% 7% 12% 26% 21% 4	2315
May	1st to 10th	Day	37% 10% 17% 23% 12% 2	4120
	11th to 20th	Day	43% 8% 12% 21% 16% 1	4085
	21st to end	Day	26% 12% 18% 21% 21% 3	4489
June	1st to 10th	Day	37% 11% 18% 23% 10% 1	2470
	11th to 20th	Day	32% 11% 19% 24% 14% 1	2470
	21st to end	Day	36% 11% 19% 22% 11% 2	2470
July	1st to 10th	Day	43% 13% 17% 19% 7% 1	4055
	11th to 20th	Day	38% 14% 30% 14% 4 1	4051
	21st to end	Day	46% 14% 18% 16% 5%	4324
August	1st to 10th	Day	55% 12% 18% 11% 4	4091
	11th to 20th	Day	39% 11% 17% 20% 13%	4030
	21st to end	Day	30% 9% 14% 32% 13% 1	4180
September	1st to 10th	Day	35% 12% 16% 16% 17% 4	2179
	11th to 20th	Day	41% 8% 11% 15% 21% 4	2090
	21st to end	Day	41% 7% 10% 20% 16% 6%	2090
October	1st to 10th	Day	33% 5% 7% 20% 28% 8%	3209
	11th to 20th	Day	19% 3 5% 17% 28% 28%	3140
	21st to end	Day	25% 3 5% 21% 29% 17%	3428
November	1st to 10th	Day	32% 4 7% 19% 26% 11%	1957
	11th to 20th	Day	35% 5% 7% 18% 25% 10%	1858
	21st to end	Day	36% 5% 9% 19% 23% 9%	1710
December	1st to 10th	Day	45% 5% 10% 17% 17% 5%	1710
	11th to 20th	Day	33% 4 7% 23% 24% 9%	2150
	21st to end	Day	41% 6% 7% 20% 23% 3	3124
January	1st to 10th	Night	36% 5% 9% 18% 24% 8%	4109
	11th to 20th	Night	37% 7% 8% 18% 24% 6%	4120
	21st to end	Night	41% 6% 6% 14% 26% 8%	4532
February	1st to 10th	Night	40% 5% 9% 18% 19% 9%	2470
	11th to 20th	Night	44% 5% 7% 16% 21% 8%	2275
	21st to end	Night	39% 6% 9% 17% 19% 10%	1771
March	1st to 10th	Night	52% 7% 9% 12% 13% 7%	3418
	11th to 20th	Night	32% 6% 9% 14% 24% 16%	3480
	21st to end	Night	37% 6% 9% 21% 19% 8%	3817
April	1st to 10th	Night	33% 6% 12% 18% 21% 10%	2062
	11th to 20th	Night	31% 6% 11% 19% 21% 11%	1875
	21st to end	Night	29% 7% 13% 23% 23% 5%	1879
May	1st to 10th	Night	32% 12% 15% 24% 14% 2	2840
	11th to 20th	Night	39% 9% 15% 20% 16%	2813
	21st to end	Night	27% 14% 15% 25% 17% 2	3087
June	1st to 10th	Night	38% 14% 16% 21% 9% 2	1710
	11th to 20th	Night	37% 11% 19% 20% 12% 2	1710
	21st to end	Night	34% 14% 21% 20% 9% 2	1710
July	1st to 10th	Night	45% 14% 18% 16% 6% 2	2795
	11th to 20th	Night	44% 16% 25% 11% 4 1	2786
	21st to end	Night	53% 13% 15% 14% 4	2988
August	1st to 10th	Night	54% 10% 20% 13% 2 1	2814
	11th to 20th	Night	43% 11% 19% 20% 6%	2830
	21st to end	Night	27% 8% 16% 33% 15% 1	3476
September	1st to 10th	Night	37% 12% 15% 17% 14% 5%	1997
	11th to 20th	Night	45% 8% 11% 16% 17% 4	2090
	21st to end	Night	43% 8% 12% 18% 16% 4	2090
October	1st to 10th	Night	34% 5% 9% 19% 26% 7%	3736
	11th to 20th	Night	20% 3 6% 15% 26% 31%	3779
	21st to end	Night	24% 5% 6% 21% 27% 18%	4120
November	1st to 10th	Night	33% 4 8% 15% 26% 13%	2341
	11th to 20th	Night	34% 5% 7% 15% 26% 13%	2325
	21st to end	Night	36% 4 9% 20% 23% 10%	2470
December	1st to 10th	Night	42% 6% 10% 15% 19% 7%	2470
	11th to 20th	Night	37% 4 7% 19% 24% 9%	3044
	21st to end	Night	42% 5% 8% 18% 24% 4	4532

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% 11% 43% 22% 5%	270
	11th to 20th	Day	15% 14% 38% 23% 9%	270
	21st to end	Day	22% 16% 36% 20% 6%	297
February	1st to 10th	Day	19% 13% 37% 24% 6%	270
	11th to 20th	Day	28% 12% 39% 18% 3	270
	21st to end	Day	21% 15% 37% 20% 6% 1	336
March	1st to 10th	Day	17% 13% 30% 27% 11%	460
	11th to 20th	Day	16% 11% 43% 23% 7% 1	460
	21st to end	Day	17% 14% 35% 23% 10% 1	506
April	1st to 10th	Day	14% 14% 32% 24% 15% 1	460
	11th to 20th	Day	11% 9% 28% 26% 19% 8%	452
	21st to end	Day	11% 7% 25% 28% 21% 8%	460
May	1st to 10th	Day	8% 10% 29% 26% 19% 8%	463
	11th to 20th	Day	14% 3 17% 28% 24% 15%	487
	21st to end	Day	12% 4 12% 23% 25% 24%	529
June	1st to 10th	Day	11% 3 11% 29% 30% 17%	490
	11th to 20th	Day	9% 2 13% 25% 29% 23%	490
	21st to end	Day	8% 1 9% 29% 30% 23%	490
July	1st to 10th	Day	9% 2 5% 20% 31% 33%	485
	11th to 20th	Day	8% 2 5% 19% 35% 31%	484
	21st to end	Day	5% 2 5% 23% 41% 23%	532
August	1st to 10th	Day	16% 2 7% 22% 29% 24%	486
	11th to 20th	Day	11% 3 6% 22% 31% 28%	479
	21st to end	Day	13% 2 9% 20% 31% 26%	539
September	1st to 10th	Day	9% 3 8% 25% 34% 22%	490
	11th to 20th	Day	16% 3 13% 21% 30% 17%	490
	21st to end	Day	18% 2 11% 27% 29% 12%	490
October	1st to 10th	Day	15% 3 20% 27% 24% 11%	490
	11th to 20th	Day	10% 5% 23% 28% 25% 9%	490
	21st to end	Day	12% 4 24% 27% 24% 9%	539
November	1st to 10th	Day	16% 5% 24% 30% 18% 7%	495
	11th to 20th	Day	18% 6% 33% 27% 14% 2	418
	21st to end	Day	11% 7% 34% 29% 16% 4	270
December	1st to 10th	Day	22% 11% 33% 24% 9% 1	270
	11th to 20th	Day	19% 10% 31% 24% 14% 1	270
	21st to end	Day	23% 12% 34% 18% 10% 3	297
January	1st to 10th	Night	18% 11% 35% 27% 8% 1	760
	11th to 20th	Night	16% 11% 32% 33% 8%	760
	21st to end	Night	18% 8% 39% 32% 2	836
February	1st to 10th	Night	18% 9% 34% 33% 6%	760
	11th to 20th	Night	21% 11% 37% 30% 2	743
	21st to end	Night	17% 13% 36% 29% 6%	628
March	1st to 10th	Night	18% 9% 32% 33% 8%	760
	11th to 20th	Night	16% 10% 34% 32% 8%	760
	21st to end	Night	15% 8% 37% 31% 8%	836
April	1st to 10th	Night	14% 13% 35% 29% 9%	760
	11th to 20th	Night	12% 10% 30% 33% 15% 1	751
	21st to end	Night	10% 8% 29% 40% 13%	739
May	1st to 10th	Night	11% 5% 29% 40% 15%	570
	11th to 20th	Night	12% 5% 24% 40% 18% 2	561
	21st to end	Night	9% 2 11% 38% 36% 3	617
June	1st to 10th	Night	13% 3 11% 42% 28% 3	570
	11th to 20th	Night	10% 2 11% 37% 31% 9%	570
	21st to end	Night	8% 2 11% 38% 34% 8%	570
July	1st to 10th	Night	9% 2 8% 31% 44% 6%	555
	11th to 20th	Night	11% 1 5% 28% 48% 7%	552
	21st to end	Night	6% 3 5% 35% 44% 7%	624
August	1st to 10th	Night	14% 2 7% 26% 45% 7%	567
	11th to 20th	Night	13% 2 5% 34% 40% 6%	569
	21st to end	Night	13% 2 7% 30% 43% 6%	836
September	1st to 10th	Night	11% 1 8% 31% 43% 6%	760
	11th to 20th	Night	16% 3 8% 33% 35% 6%	760
	21st to end	Night	20% 2 13% 33% 30% 3	760
October	1st to 10th	Night	15% 3 17% 31% 29% 4	760
	11th to 20th	Night	13% 5% 21% 34% 25% 2	760
	21st to end	Night	11% 5% 23% 34% 23% 2	836
November	1st to 10th	Night	13% 5% 23% 36% 18% 4	780
	11th to 20th	Night	18% 7% 28% 34% 12% 1	763
	21st to end	Night	15% 6% 29% 32% 17% 1	760
December	1st to 10th	Night	21% 9% 26% 34% 9% 1	760
	11th to 20th	Night	18% 6% 27% 36% 12% 1	760
	21st to end	Night	25% 9% 24% 32% 10% 1	836

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