Lost Maples State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lost Maples State Natural Area clear sky chart from 2005-11-06 to 2026-05-17.

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 5% 4 4 4 3 5% 7% 49%	132356
	Night	13% 6% 2 4 3 3 3 3 5% 6% 52%	130820
Transparency	Day	35% 4 9% 20% 19% 12%	136213
	Night	33% 4 10% 19% 20% 14%	135027
Seeing	Day	15% 10% 25% 30% 17% 3	16734
	Night	16% 8% 27% 35% 13% 1	26774

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	10% 5% 2 4 2 3 3 3 4 6% 58%	5289
	11th to 20th	Day	12% 7% 2 4 2 2 3 3 4 5% 58%	5508
	21st to end	Day	20% 7% 2 4 3 2 2 2 4 7% 47%	6468
February	1st to 10th	Day	13% 8% 2 5% 4 3 3 2 4 6% 51%	2100
	11th to 20th	Day	14% 8% 2 5% 3 4 3 4 5% 6% 47%	2049
	21st to end	Day	14% 6% 2 4 2 3 3 3 4 6% 54%	1730
March	1st to 10th	Day	13% 6% 2 5% 3 3 2 3 4 6% 55%	4769
	11th to 20th	Day	13% 8% 2 6% 3 3 2 2 3 5% 54%	5090
	21st to end	Day	14% 6% 2 5% 3 3 3 3 4 6% 50%	5583
April	1st to 10th	Day	14% 7% 2 6% 4 3 3 3 5% 6% 45%	2310
	11th to 20th	Day	17% 7% 2 5% 4 3 3 3 5% 6% 43%	2469
	21st to end	Day	15% 8% 3 5% 4 3 4 3 4 6% 45%	2546
May	1st to 10th	Day	19% 7% 2 6% 5% 4 4 3 5% 6% 39%	5992
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 6% 9% 47%	5941
	21st to end	Day	14% 8% 3 7% 5% 5% 5% 4 6% 8% 36%	6434
June	1st to 10th	Day	7% 5% 1 6% 4 3 4 4 6% 9% 49%	2600
	11th to 20th	Day	9% 5% 2 5% 5% 5% 5% 4 6% 8% 47%	2600
	21st to end	Day	9% 6% 2 6% 6% 5% 5% 5% 7% 9% 40%	2600
July	1st to 10th	Day	16% 8% 2 6% 4 4 4 4 6% 8% 37%	5900
	11th to 20th	Day	8% 5% 2 6% 5% 4 5% 4 6% 8% 46%	5900
	21st to end	Day	8% 5% 2 5% 4 5% 5% 4 7% 10% 46%	6385
August	1st to 10th	Day	2 2 1 3 3 3 3 3 5% 7% 68%	3905
	11th to 20th	Day	4 3 1 3 3 4 4 3 6% 9% 60%	3846
	21st to end	Day	5% 4 2 6% 5% 5% 5% 4 6% 9% 49%	4289
September	1st to 10th	Day	12% 7% 3 7% 6% 5% 5% 3 6% 6% 41%	2200
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 5% 6% 7% 43%	2200
	21st to end	Day	8% 6% 2 6% 4 4 5% 4 6% 7% 47%	2200
October	1st to 10th	Day	7% 5% 2 5% 4 3 4 3 5% 8% 54%	2200
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 4 5% 53%	2180
	21st to end	Day	12% 5% 2 5% 3 2 3 2 3 4 58%	2200
November	1st to 10th	Day	14% 7% 2 6% 4 3 3 3 4 6% 49%	1995
	11th to 20th	Day	11% 7% 2 5% 3 4 3 3 4 6% 52%	1890
	21st to end	Day	16% 8% 2 6% 3 3 3 2 4 5% 48%	1890
December	1st to 10th	Day	22% 9% 3 6% 3 3 3 2 3 5% 41%	3030
	11th to 20th	Day	15% 9% 3 5% 4 4 3 3 5% 5% 45%	3481
	21st to end	Day	12% 6% 2 4 2 2 2 2 3 4 61%	4587
January	1st to 10th	Night	11% 4 1 4 2 3 3 2 4 6% 59%	7634
	11th to 20th	Night	10% 4 1 3 2 2 2 2 5% 5% 64%	7523
	21st to end	Night	25% 7% 2 4 2 2 2 2 3 4 45%	7746
February	1st to 10th	Night	13% 7% 2 4 3 2 2 2 5% 6% 54%	2520
	11th to 20th	Night	15% 7% 2 4 3 2 3 3 4 5% 51%	2458
	21st to end	Night	14% 5% 2 5% 3 2 3 3 5% 6% 51%	2076
March	1st to 10th	Night	12% 8% 2 5% 3 3 4 3 5% 7% 50%	5314
	11th to 20th	Night	11% 9% 2 5% 3 2 3 2 3 5% 54%	5090
	21st to end	Night	14% 11% 2 4 3 2 3 3 4 5% 49%	5588
April	1st to 10th	Night	11% 8% 2 5% 4 3 3 3 5% 6% 50%	2310
	11th to 20th	Night	18% 6% 3 6% 3 3 4 3 4 5% 46%	2096
	21st to end	Night	19% 8% 2 4 4 2 3 3 4 5% 45%	2072
May	1st to 10th	Night	22% 9% 2 5% 3 3 3 3 4 5% 40%	4143
	11th to 20th	Night	9% 5% 2 5% 4 4 4 4 5% 8% 52%	4107
	21st to end	Night	14% 8% 2 5% 3 4 4 4 6% 10% 40%	4443
June	1st to 10th	Night	4 3 1 3 3 3 3 4 7% 10% 60%	1800
	11th to 20th	Night	6% 5% 2 3 3 3 4 5% 5% 8% 57%	1800
	21st to end	Night	7% 5% 1 5% 4 4 3 3 5% 10% 52%	1800
July	1st to 10th	Night	15% 6% 2 5% 4 4 5% 4 6% 9% 41%	4078
	11th to 20th	Night	8% 5% 2 5% 3 4 4 4 6% 9% 52%	4077
	21st to end	Night	9% 6% 2 5% 4 3 3 4 5% 9% 50%	4481
August	1st to 10th	Night	2 2 1 2 2 2 3 3 5% 7% 72%	3255
	11th to 20th	Night	3 2 1 3 2 3 4 4 6% 10% 62%	3213
	21st to end	Night	6% 5% 2 4 3 4 4 4 7% 10% 52%	3619
September	1st to 10th	Night	10% 6% 2 5% 3 5% 4 3 5% 9% 48%	2200
	11th to 20th	Night	11% 7% 2 5% 4 3 4 4 5% 8% 47%	2200
	21st to end	Night	8% 5% 2 5% 4 3 4 3 5% 8% 52%	2200
October	1st to 10th	Night	7% 4 2 4 4 3 3 3 4 8% 60%	2200
	11th to 20th	Night	13% 5% 1 4 3 2 3 2 4 6% 56%	2200
	21st to end	Night	14% 4 1 3 2 2 2 2 3 4 64%	2640
November	1st to 10th	Night	12% 7% 1 4 3 3 2 2 4 6% 57%	2518
	11th to 20th	Night	10% 7% 2 4 3 3 2 3 4 5% 57%	2730
	21st to end	Night	17% 6% 1 4 3 3 3 3 5% 6% 50%	2730
December	1st to 10th	Night	23% 7% 3 5% 3 3 4 3 4 5% 41%	4380
	11th to 20th	Night	20% 8% 2 4 3 3 3 2 3 4 50%	4946
	21st to end	Night	15% 7% 1 3 2 2 2 2 3 6% 58%	6633

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	28% 3 5% 21% 27% 16%	5290
	11th to 20th	Day	32% 1 4 14% 25% 24%	5508
	21st to end	Day	40% 3 4 15% 26% 12%	6468
February	1st to 10th	Day	38% 3 5% 12% 22% 20%	2100
	11th to 20th	Day	39% 4 5% 18% 20% 15%	2059
	21st to end	Day	33% 3 6% 16% 24% 18%	1730
March	1st to 10th	Day	34% 2 5% 15% 17% 28%	4769
	11th to 20th	Day	37% 2 4 9% 15% 33%	5090
	21st to end	Day	36% 3 7% 18% 19% 17%	5585
April	1st to 10th	Day	40% 4 8% 16% 17% 15%	2310
	11th to 20th	Day	41% 4 7% 17% 17% 14%	2469
	21st to end	Day	42% 4 8% 18% 16% 12%	2546
May	1st to 10th	Day	45% 5% 8% 18% 17% 7%	6030
	11th to 20th	Day	33% 5% 11% 18% 22% 11%	5945
	21st to end	Day	44% 6% 10% 24% 14% 3	6447
June	1st to 10th	Day	30% 5% 15% 28% 19% 3	2600
	11th to 20th	Day	34% 6% 11% 25% 18% 5%	2600
	21st to end	Day	39% 7% 12% 23% 15% 4	2600
July	1st to 10th	Day	44% 7% 16% 28% 6%	5836
	11th to 20th	Day	34% 7% 14% 31% 12% 1	5831
	21st to end	Day	30% 8% 18% 25% 17% 1	6203
August	1st to 10th	Day	16% 4 11% 41% 27% 1	3892
	11th to 20th	Day	21% 5% 22% 39% 11% 2	3882
	21st to end	Day	29% 9% 16% 25% 19% 2	4288
September	1st to 10th	Day	43% 6% 10% 18% 17% 7%	2200
	11th to 20th	Day	38% 7% 12% 22% 17% 5%	2200
	21st to end	Day	35% 5% 10% 20% 18% 12%	2200
October	1st to 10th	Day	19% 3 7% 14% 26% 31%	3590
	11th to 20th	Day	29% 4 6% 17% 21% 22%	3536
	21st to end	Day	28% 3 5% 15% 35% 13%	3538
November	1st to 10th	Day	37% 4 8% 19% 20% 12%	1995
	11th to 20th	Day	35% 4 6% 18% 20% 18%	1890
	21st to end	Day	41% 2 5% 17% 21% 14%	1890
December	1st to 10th	Day	48% 3 6% 16% 16% 11%	3030
	11th to 20th	Day	41% 4 6% 14% 19% 15%	3479
	21st to end	Day	30% 2 3 17% 28% 20%	4587
January	1st to 10th	Night	28% 3 6% 17% 30% 16%	7635
	11th to 20th	Night	23% 2 3 15% 30% 26%	7523
	21st to end	Night	46% 2 3 10% 22% 17%	7746
February	1st to 10th	Night	33% 3 7% 14% 22% 22%	2520
	11th to 20th	Night	36% 3 6% 18% 20% 16%	2458
	21st to end	Night	35% 3 7% 15% 23% 18%	2076
March	1st to 10th	Night	35% 3 6% 17% 18% 20%	5314
	11th to 20th	Night	35% 3 5% 11% 16% 30%	5090
	21st to end	Night	39% 3 7% 17% 18% 17%	5588
April	1st to 10th	Night	35% 5% 10% 16% 16% 17%	2310
	11th to 20th	Night	41% 4 9% 14% 17% 16%	2096
	21st to end	Night	43% 3 9% 17% 16% 12%	2072
May	1st to 10th	Night	47% 4 8% 16% 13% 12%	4170
	11th to 20th	Night	30% 4 12% 20% 20% 14%	4108
	21st to end	Night	40% 6% 14% 24% 12% 5%	4452
June	1st to 10th	Night	20% 6% 19% 33% 19% 2	1800
	11th to 20th	Night	26% 6% 15% 27% 21% 6%	1800
	21st to end	Night	29% 6% 19% 27% 16% 4	1800
July	1st to 10th	Night	39% 9% 20% 27% 5%	4035
	11th to 20th	Night	28% 8% 20% 29% 14% 1	4026
	21st to end	Night	31% 7% 20% 26% 14% 1	4352
August	1st to 10th	Night	13% 5% 16% 43% 23% 1	3244
	11th to 20th	Night	17% 7% 28% 36% 9% 1	3243
	21st to end	Night	26% 10% 19% 27% 16% 2	3619
September	1st to 10th	Night	34% 7% 12% 22% 18% 7%	2200
	11th to 20th	Night	35% 7% 18% 21% 15% 6%	2200
	21st to end	Night	31% 6% 12% 22% 18% 12%	2200
October	1st to 10th	Night	17% 3 8% 16% 23% 34%	3590
	11th to 20th	Night	25% 3 8% 16% 29% 19%	3570
	21st to end	Night	26% 2 5% 18% 34% 15%	4252
November	1st to 10th	Night	32% 3 7% 19% 24% 15%	2518
	11th to 20th	Night	30% 3 7% 21% 21% 18%	2730
	21st to end	Night	36% 4 7% 16% 20% 16%	2730
December	1st to 10th	Night	46% 4 8% 15% 14% 14%	4380
	11th to 20th	Night	41% 3 5% 12% 21% 19%	4947
	21st to end	Night	32% 2 4 16% 27% 19%	6633

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	24% 14% 37% 18% 6% 1	330
	11th to 20th	Day	23% 17% 34% 19% 6% 1	330
	21st to end	Day	23% 21% 32% 19% 5%	363
February	1st to 10th	Day	27% 13% 32% 20% 8%	330
	11th to 20th	Day	24% 19% 35% 18% 5%	330
	21st to end	Day	23% 19% 40% 16% 2	273
March	1st to 10th	Day	25% 22% 37% 14% 2	330
	11th to 20th	Day	22% 22% 39% 14% 4	330
	21st to end	Day	19% 18% 43% 15% 4 1	363
April	1st to 10th	Day	25% 19% 35% 21% 1	330
	11th to 20th	Day	21% 20% 40% 16% 3	507
	21st to end	Day	19% 16% 44% 17% 3	566
May	1st to 10th	Day	22% 13% 39% 22% 4	753
	11th to 20th	Day	17% 13% 36% 27% 6% 1	756
	21st to end	Day	19% 11% 35% 27% 9%	789
June	1st to 10th	Day	7% 5% 24% 45% 18% 1	730
	11th to 20th	Day	12% 4 25% 43% 15% 1	730
	21st to end	Day	11% 3 17% 37% 26% 5%	730
July	1st to 10th	Day	14% 5% 12% 37% 27% 5%	721
	11th to 20th	Day	8% 2 8% 42% 35% 5%	718
	21st to end	Day	6% 2 9% 42% 35% 6%	782
August	1st to 10th	Day	1 1 6% 48% 37% 7%	527
	11th to 20th	Day	7% 1 8% 39% 37% 8%	517
	21st to end	Day	5% 3 6% 36% 40% 9%	573
September	1st to 10th	Day	11% 2 11% 33% 36% 8%	330
	11th to 20th	Day	6% 1 8% 36% 44% 6%	330
	21st to end	Day	9% 2 12% 38% 34% 6%	330
October	1st to 10th	Day	7% 4 14% 41% 30% 5%	330
	11th to 20th	Day	12% 4 23% 42% 18% 2	330
	21st to end	Day	18% 15% 26% 28% 11% 2	363
November	1st to 10th	Day	19% 8% 33% 27% 13% 1	330
	11th to 20th	Day	20% 9% 31% 25% 11% 4	330
	21st to end	Day	25% 16% 34% 15% 9% 2	330
December	1st to 10th	Day	19% 15% 31% 25% 8% 1	330
	11th to 20th	Day	20% 18% 31% 21% 8% 1	330
	21st to end	Day	18% 16% 31% 28% 7% 1	363
January	1st to 10th	Night	17% 11% 30% 34% 7% 1	1050
	11th to 20th	Night	20% 12% 30% 32% 6%	997
	21st to end	Night	24% 11% 28% 30% 7%	924
February	1st to 10th	Night	21% 12% 30% 30% 6%	840
	11th to 20th	Night	23% 13% 32% 27% 4	824
	21st to end	Night	21% 12% 40% 24% 2	692
March	1st to 10th	Night	25% 13% 33% 24% 4	764
	11th to 20th	Night	20% 12% 35% 28% 5%	630
	21st to end	Night	20% 11% 42% 23% 4	693
April	1st to 10th	Night	13% 16% 44% 24% 2	630
	11th to 20th	Night	21% 16% 41% 20% 2	623
	21st to end	Night	23% 12% 43% 19% 4	630
May	1st to 10th	Night	18% 12% 42% 24% 3	630
	11th to 20th	Night	17% 9% 36% 32% 6%	609
	21st to end	Night	17% 9% 36% 31% 7%	650
June	1st to 10th	Night	5% 3 31% 46% 14%	600
	11th to 20th	Night	10% 3 36% 43% 8%	600
	21st to end	Night	9% 4 26% 42% 18% 1	600
July	1st to 10th	Night	12% 4 14% 48% 21% 1	585
	11th to 20th	Night	6% 2 16% 49% 25% 2	582
	21st to end	Night	7% 2 11% 51% 27% 1	657
August	1st to 10th	Night	3 1 9% 53% 32% 1	597
	11th to 20th	Night	5% 1 7% 51% 34% 2	594
	21st to end	Night	8% 2 9% 42% 36% 3	660
September	1st to 10th	Night	10% 2 9% 44% 33% 2	600
	11th to 20th	Night	12% 1 11% 42% 33% 2	600
	21st to end	Night	9% 3 14% 40% 31% 4	600
October	1st to 10th	Night	9% 3 13% 44% 30% 1	600
	11th to 20th	Night	16% 5% 22% 36% 20% 2	600
	21st to end	Night	16% 8% 24% 30% 19% 2	880
November	1st to 10th	Night	17% 5% 22% 37% 17% 2	878
	11th to 20th	Night	14% 8% 24% 38% 14% 2	1050
	21st to end	Night	21% 10% 26% 31% 11% 1	1050
December	1st to 10th	Night	19% 8% 27% 35% 10% 1	1050
	11th to 20th	Night	24% 11% 26% 31% 8%	1050
	21st to end	Night	18% 11% 28% 35% 8%	1155

Page generated at 2026-05-14 00:58:58. Version ac07

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