Lesterville
Clear Sky Chart
History

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

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	11% 7% 3 7% 4 4 4 4 5% 7% 45%	135354
	Night	9% 7% 2 7% 4 4 4 3 5% 7% 47%	132317
Transparency	Day	38% 6% 14% 25% 15% 2	130033
	Night	36% 6% 14% 26% 17% 2	128645
Seeing	Day	14% 9% 30% 31% 14% 2	17339
	Night	13% 8% 34% 35% 10% 1	27203

By Month

Percentage Cloud Cover SW (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% 12% 5% 15% 8% 7% 6% 4 4 4 26%	3638
	11th to 20th	Day	5% 11% 4 11% 8% 5% 6% 4 7% 6% 33%	3684
	21st to end	Day	4 9% 6% 10% 6% 4 5% 4 5% 5% 42%	4488
February	1st to 10th	Day	10% 12% 4 9% 7% 6% 6% 4 5% 6% 32%	1800
	11th to 20th	Day	9% 11% 5% 8% 5% 5% 4 4 4 6% 38%	1834
	21st to end	Day	10% 10% 3 8% 6% 4 5% 3 5% 7% 38%	1650
March	1st to 10th	Day	10% 7% 4 8% 4 4 3 3 3 5% 48%	4676
	11th to 20th	Day	8% 7% 2 6% 3 3 3 3 4 8% 52%	4980
	21st to end	Day	22% 11% 4 10% 5% 4 5% 3 5% 6% 24%	5464
April	1st to 10th	Day	16% 7% 3 7% 4 4 5% 4 5% 6% 40%	2268
	11th to 20th	Day	18% 8% 3 5% 4 4 4 3 5% 6% 40%	2569
	21st to end	Day	20% 8% 2 7% 3 4 4 3 4 6% 39%	2600
May	1st to 10th	Day	11% 6% 2 5% 4 4 5% 4 6% 7% 48%	5900
	11th to 20th	Day	15% 6% 2 5% 4 3 3 3 4 5% 50%	5862
	21st to end	Day	19% 8% 3 6% 4 4 4 4 6% 7% 36%	6629
June	1st to 10th	Day	11% 4 2 4 4 4 4 4 5% 7% 50%	2950
	11th to 20th	Day	13% 6% 2 4 3 3 4 4 6% 8% 47%	3000
	21st to end	Day	7% 5% 2 5% 3 4 5% 4 6% 9% 50%	3000
July	1st to 10th	Day	8% 4 2 5% 4 4 5% 4 7% 10% 47%	6444
	11th to 20th	Day	10% 5% 2 5% 3 3 4 3 5% 8% 52%	6340
	21st to end	Day	7% 5% 2 5% 4 4 4 4 7% 9% 50%	6433
August	1st to 10th	Day	8% 6% 2 7% 4 5% 5% 4 7% 9% 43%	5801
	11th to 20th	Day	12% 6% 2 5% 4 4 4 4 6% 8% 45%	5821
	21st to end	Day	9% 4 2 5% 3 4 4 3 4 7% 55%	6490
September	1st to 10th	Day	13% 5% 1 5% 2 3 3 3 5% 6% 54%	2294
	11th to 20th	Day	8% 4 1 4 4 3 3 4 5% 7% 56%	2200
	21st to end	Day	11% 4 2 4 3 3 3 3 5% 6% 58%	2200
October	1st to 10th	Day	9% 3 1 3 3 2 3 2 4 4 66%	3427
	11th to 20th	Day	8% 4 2 5% 3 3 4 3 4 7% 58%	3240
	21st to end	Day	10% 7% 2 6% 3 4 4 3 6% 8% 46%	3332
November	1st to 10th	Day	8% 7% 2 6% 4 4 5% 4 6% 7% 46%	1853
	11th to 20th	Day	9% 6% 2 8% 6% 4 4 3 5% 7% 46%	1819
	21st to end	Day	10% 8% 2 8% 4 4 3 4 5% 8% 43%	1600
December	1st to 10th	Day	5% 7% 3 9% 7% 6% 5% 4 5% 7% 42%	2610
	11th to 20th	Day	7% 11% 4 9% 4 5% 5% 5% 6% 6% 38%	2850
	21st to end	Day	13% 9% 4 15% 5% 4 4 3 5% 7% 31%	3608
January	1st to 10th	Night	9% 12% 4 13% 10% 7% 6% 5% 5% 5% 24%	6327
	11th to 20th	Night	3 10% 4 9% 6% 6% 7% 4 7% 6% 37%	6280
	21st to end	Night	4 8% 5% 9% 5% 5% 5% 4 6% 6% 44%	6490
February	1st to 10th	Night	10% 10% 4 8% 6% 5% 4 3 5% 6% 38%	2600
	11th to 20th	Night	7% 12% 4 8% 4 4 4 4 5% 6% 42%	2469
	21st to end	Night	9% 8% 3 6% 5% 5% 4 3 6% 5% 46%	1980
March	1st to 10th	Night	12% 6% 2 4 3 3 4 3 5% 7% 52%	5190
	11th to 20th	Night	11% 6% 2 5% 3 3 3 2 5% 9% 53%	4980
	21st to end	Night	16% 10% 3 8% 5% 4 4 3 5% 6% 35%	5467
April	1st to 10th	Night	13% 8% 2 6% 3 4 4 3 6% 7% 42%	2129
	11th to 20th	Night	14% 7% 3 5% 4 3 4 4 5% 7% 44%	1779
	21st to end	Night	17% 6% 2 6% 4 4 4 4 6% 6% 42%	1800
May	1st to 10th	Night	13% 4 2 4 3 3 4 3 5% 7% 52%	4080
	11th to 20th	Night	13% 5% 2 5% 3 3 4 3 5% 7% 51%	4053
	21st to end	Night	17% 8% 2 5% 3 3 4 3 5% 8% 41%	4253
June	1st to 10th	Night	8% 4 2 4 4 4 4 3 6% 8% 54%	1446
	11th to 20th	Night	8% 4 1 5% 4 4 3 4 6% 9% 52%	1400
	21st to end	Night	7% 3 2 4 3 3 3 4 6% 8% 56%	1400
July	1st to 10th	Night	7% 4 2 5% 4 3 3 4 6% 8% 52%	3516
	11th to 20th	Night	8% 5% 1 5% 3 4 3 3 5% 7% 56%	3640
	21st to end	Night	5% 3 1 4 4 4 4 4 7% 10% 55%	4439
August	1st to 10th	Night	6% 5% 2 6% 4 4 5% 4 6% 11% 46%	4011
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 6% 8% 50%	4028
	21st to end	Night	7% 4 2 5% 4 4 4 3 5% 9% 54%	4487
September	1st to 10th	Night	8% 4 1 4 4 3 4 3 4 6% 59%	2102
	11th to 20th	Night	8% 4 2 4 3 3 4 3 5% 8% 58%	2200
	21st to end	Night	8% 4 1 4 3 3 3 3 3 6% 62%	2200
October	1st to 10th	Night	9% 3 1 2 2 1 1 2 3 4 71%	3719
	11th to 20th	Night	9% 4 1 3 3 3 2 2 5% 7% 62%	3899
	21st to end	Night	11% 6% 2 5% 4 4 4 3 5% 7% 48%	4461
November	1st to 10th	Night	9% 4 2 5% 4 3 4 3 5% 7% 54%	2665
	11th to 20th	Night	8% 7% 2 6% 5% 4 4 3 6% 7% 49%	2732
	21st to end	Night	9% 7% 2 6% 3 4 4 4 6% 7% 49%	2800
December	1st to 10th	Night	5% 7% 3 8% 5% 5% 4 3 4 6% 48%	4580
	11th to 20th	Night	8% 9% 3 9% 6% 6% 5% 4 5% 7% 38%	5350
	21st to end	Night	14% 11% 4 12% 5% 4 4 4 4 5% 32%	7365

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	59% 6% 15% 14% 6%	3639
	11th to 20th	Day	49% 4 14% 17% 14% 1	3684
	21st to end	Day	42% 6% 18% 21% 11% 2	4488
February	1st to 10th	Day	52% 8% 14% 17% 9% 1	1800
	11th to 20th	Day	47% 6% 12% 21% 13% 2	1843
	21st to end	Day	45% 6% 15% 20% 11% 2	1650
March	1st to 10th	Day	38% 5% 10% 30% 14% 2	4676
	11th to 20th	Day	31% 5% 11% 29% 22% 2	4980
	21st to end	Day	59% 6% 14% 16% 4 2	5464
April	1st to 10th	Day	44% 5% 13% 24% 12% 1	2268
	11th to 20th	Day	44% 7% 11% 22% 14% 2	2572
	21st to end	Day	45% 7% 12% 23% 13%	2600
May	1st to 10th	Day	32% 7% 11% 26% 24% 1	5900
	11th to 20th	Day	36% 6% 11% 22% 16% 9%	5866
	21st to end	Day	46% 7% 11% 24% 12% 1	6630
June	1st to 10th	Day	32% 7% 17% 29% 12% 2	2950
	11th to 20th	Day	35% 7% 16% 23% 16% 3	3000
	21st to end	Day	28% 8% 17% 29% 15% 3	3000
July	1st to 10th	Day	31% 6% 19% 29% 13% 1	6376
	11th to 20th	Day	31% 6% 12% 32% 17% 3	6265
	21st to end	Day	29% 7% 19% 26% 17% 2	6248
August	1st to 10th	Day	32% 7% 15% 30% 13% 2	4220
	11th to 20th	Day	43% 7% 13% 25% 10% 1	4210
	21st to end	Day	28% 7% 17% 26% 19% 3	4674
September	1st to 10th	Day	32% 6% 12% 28% 18% 3	2294
	11th to 20th	Day	27% 6% 16% 33% 17% 1	2200
	21st to end	Day	27% 6% 11% 31% 23% 3	2200
October	1st to 10th	Day	23% 3 8% 25% 38% 4	3427
	11th to 20th	Day	27% 4 14% 29% 20% 5%	3240
	21st to end	Day	36% 4 13% 25% 19% 3	3332
November	1st to 10th	Day	35% 6% 17% 26% 14% 2	1853
	11th to 20th	Day	38% 6% 16% 25% 14% 2	1819
	21st to end	Day	40% 4 16% 26% 13% 1	1600
December	1st to 10th	Day	40% 6% 17% 26% 9% 1	2610
	11th to 20th	Day	46% 6% 19% 20% 9%	2847
	21st to end	Day	52% 5% 12% 24% 5% 1	3608
January	1st to 10th	Night	58% 6% 12% 15% 8%	6327
	11th to 20th	Night	43% 6% 15% 19% 15% 2	6280
	21st to end	Night	38% 6% 14% 27% 14%	6490
February	1st to 10th	Night	45% 6% 15% 21% 11% 1	2600
	11th to 20th	Night	43% 5% 15% 21% 12% 4	2470
	21st to end	Night	39% 5% 14% 26% 13% 4	1980
March	1st to 10th	Night	32% 4 11% 30% 21% 2	5190
	11th to 20th	Night	30% 4 9% 28% 25% 3	4980
	21st to end	Night	49% 7% 14% 23% 7% 1	5467
April	1st to 10th	Night	40% 6% 14% 24% 14% 1	2129
	11th to 20th	Night	39% 5% 10% 24% 20% 2	1779
	21st to end	Night	41% 8% 12% 24% 13% 2	1800
May	1st to 10th	Night	30% 6% 13% 25% 25% 2	4080
	11th to 20th	Night	32% 6% 12% 21% 20% 9%	4054
	21st to end	Night	41% 5% 11% 28% 13% 1	4254
June	1st to 10th	Night	27% 8% 16% 29% 19% 3	1446
	11th to 20th	Night	28% 7% 16% 24% 21% 4	1400
	21st to end	Night	24% 7% 16% 31% 19% 3	1400
July	1st to 10th	Night	29% 5% 19% 31% 14% 3	3476
	11th to 20th	Night	28% 5% 12% 35% 16% 3	3592
	21st to end	Night	23% 8% 21% 29% 17% 3	4311
August	1st to 10th	Night	30% 7% 16% 30% 15% 2	2916
	11th to 20th	Night	33% 7% 15% 28% 15% 2	2915
	21st to end	Night	27% 6% 17% 24% 22% 5%	3234
September	1st to 10th	Night	26% 6% 13% 27% 22% 5%	2102
	11th to 20th	Night	25% 5% 15% 32% 21% 2	2200
	21st to end	Night	24% 5% 10% 31% 26% 4	2200
October	1st to 10th	Night	20% 3 6% 20% 47% 4	3719
	11th to 20th	Night	24% 3 11% 31% 25% 5%	3899
	21st to end	Night	35% 4 13% 27% 19% 1	4461
November	1st to 10th	Night	30% 5% 15% 25% 21% 4	2665
	11th to 20th	Night	33% 6% 15% 25% 18% 3	2732
	21st to end	Night	33% 6% 16% 28% 16% 1	2800
December	1st to 10th	Night	37% 4 15% 32% 11% 1	4580
	11th to 20th	Night	44% 7% 15% 25% 7%	5352
	21st to end	Night	54% 5% 13% 22% 7%	7365

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% 10% 29% 30% 10% 3	300
	11th to 20th	Day	14% 13% 36% 29% 7% 1	300
	21st to end	Day	14% 9% 42% 24% 10% 2	330
February	1st to 10th	Day	11% 21% 38% 26% 4	300
	11th to 20th	Day	14% 12% 41% 24% 7% 2	300
	21st to end	Day	15% 13% 37% 30% 4	249
March	1st to 10th	Day	14% 12% 41% 29% 3 2	300
	11th to 20th	Day	18% 11% 37% 22% 11% 1	300
	21st to end	Day	28% 12% 32% 22% 5% 2	330
April	1st to 10th	Day	23% 15% 38% 19% 4	368
	11th to 20th	Day	21% 18% 28% 26% 6%	690
	21st to end	Day	24% 12% 30% 23% 8% 2	700
May	1st to 10th	Day	16% 14% 29% 27% 12% 2	703
	11th to 20th	Day	18% 10% 29% 25% 17% 2	725
	21st to end	Day	18% 9% 29% 28% 12% 3	789
June	1st to 10th	Day	9% 8% 25% 32% 21% 5%	730
	11th to 20th	Day	13% 6% 35% 29% 15% 2	730
	21st to end	Day	10% 6% 29% 36% 17% 2	730
July	1st to 10th	Day	7% 3 22% 35% 27% 5%	721
	11th to 20th	Day	7% 3 25% 43% 19% 3	718
	21st to end	Day	6% 3 23% 46% 19% 4	794
August	1st to 10th	Day	8% 3 23% 41% 21% 3	726
	11th to 20th	Day	11% 3 22% 37% 22% 5%	715
	21st to end	Day	8% 3 27% 37% 22% 4	803
September	1st to 10th	Day	14% 5% 26% 35% 17% 3	424
	11th to 20th	Day	8% 5% 36% 31% 17% 3	330
	21st to end	Day	15% 10% 27% 28% 15% 5%	330
October	1st to 10th	Day	18% 7% 28% 29% 16% 3	330
	11th to 20th	Day	16% 15% 35% 23% 9% 2	330
	21st to end	Day	20% 14% 35% 22% 8% 1	363
November	1st to 10th	Day	17% 10% 35% 25% 8% 4	330
	11th to 20th	Day	15% 15% 38% 26% 6%	321
	21st to end	Day	18% 18% 29% 25% 11%	300
December	1st to 10th	Day	13% 10% 36% 30% 9% 2	300
	11th to 20th	Day	14% 13% 38% 26% 8%	300
	21st to end	Day	20% 12% 32% 29% 6%	330
January	1st to 10th	Night	12% 10% 37% 33% 8% 1	1000
	11th to 20th	Night	11% 14% 36% 31% 7% 1	1000
	21st to end	Night	13% 8% 41% 29% 8%	1100
February	1st to 10th	Night	14% 12% 40% 28% 6%	1000
	11th to 20th	Night	12% 12% 39% 32% 5%	915
	21st to end	Night	13% 8% 39% 31% 8% 1	660
March	1st to 10th	Night	12% 9% 43% 30% 5%	720
	11th to 20th	Night	14% 9% 41% 30% 6%	600
	21st to end	Night	18% 9% 41% 26% 6%	660
April	1st to 10th	Night	16% 14% 39% 29% 3	600
	11th to 20th	Night	16% 14% 37% 26% 6%	593
	21st to end	Night	18% 10% 37% 27% 8% 1	600
May	1st to 10th	Night	16% 8% 34% 31% 10%	600
	11th to 20th	Night	16% 9% 28% 36% 11%	591
	21st to end	Night	18% 5% 34% 34% 10%	650
June	1st to 10th	Night	9% 6% 27% 41% 17% 1	600
	11th to 20th	Night	10% 3 32% 42% 12% 1	600
	21st to end	Night	8% 4 26% 46% 16%	600
July	1st to 10th	Night	6% 2 21% 45% 25% 1	585
	11th to 20th	Night	7% 1 21% 54% 16%	582
	21st to end	Night	4 2 24% 53% 16%	657
August	1st to 10th	Night	8% 3 23% 48% 17% 1	597
	11th to 20th	Night	8% 3 23% 44% 21%	594
	21st to end	Night	5% 2 28% 46% 17% 1	660
September	1st to 10th	Night	10% 5% 26% 41% 16% 2	600
	11th to 20th	Night	8% 3 33% 40% 14% 3	600
	21st to end	Night	10% 6% 34% 35% 14% 1	600
October	1st to 10th	Night	19% 8% 29% 33% 12% 1	677
	11th to 20th	Night	15% 11% 37% 30% 8%	800
	21st to end	Night	16% 11% 34% 30% 8%	1001
November	1st to 10th	Night	12% 9% 37% 32% 9% 1	1025
	11th to 20th	Night	11% 12% 37% 31% 8%	1036
	21st to end	Night	12% 10% 36% 34% 8%	1000
December	1st to 10th	Night	12% 10% 39% 32% 6%	1000
	11th to 20th	Night	14% 8% 37% 32% 8%	1000
	21st to end	Night	21% 9% 34% 29% 6% 1	1100

Page generated at 2025-11-14 23:55:55. Version ac07

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