Lawrence
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lawrence 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 6% 4 4 4 3 5% 7% 46%	126404
	Night	11% 7% 2 6% 4 3 4 3 5% 7% 49%	124212
Transparency	Day	36% 6% 12% 26% 18% 3	130015
	Night	34% 5% 11% 26% 20% 4	128664
Seeing	Day	14% 10% 29% 28% 16% 4	17084
	Night	13% 9% 32% 33% 12% 1	26896

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	16% 9% 3 9% 4 3 3 4 5% 6% 37%	4077
	11th to 20th	Day	7% 9% 5% 10% 6% 7% 4 3 4 5% 41%	4080
	21st to end	Day	12% 13% 5% 7% 4 4 4 3 4 4 40%	4488
February	1st to 10th	Day	13% 12% 4 8% 5% 4 3 3 4 6% 40%	1800
	11th to 20th	Day	12% 9% 3 8% 5% 4 4 3 5% 5% 42%	1774
	21st to end	Day	10% 9% 2 6% 4 3 4 4 5% 7% 46%	1693
March	1st to 10th	Day	13% 8% 2 5% 3 3 2 2 3 6% 53%	4936
	11th to 20th	Day	10% 6% 1 5% 3 3 3 3 4 6% 56%	4980
	21st to end	Day	12% 10% 4 7% 5% 5% 4 3 5% 7% 37%	5462
April	1st to 10th	Day	14% 7% 2 6% 4 3 3 3 4 6% 47%	2280
	11th to 20th	Day	14% 9% 3 7% 4 4 4 4 5% 6% 41%	2374
	21st to end	Day	18% 8% 3 7% 5% 5% 4 3 4 6% 36%	2586
May	1st to 10th	Day	14% 8% 3 6% 4 3 4 3 4 6% 45%	5862
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 5% 7% 47%	5862
	21st to end	Day	18% 6% 2 6% 4 4 4 3 5% 7% 41%	6434
June	1st to 10th	Day	6% 5% 1 5% 4 4 5% 5% 7% 10% 49%	2755
	11th to 20th	Day	7% 5% 2 5% 4 5% 4 5% 7% 9% 48%	2800
	21st to end	Day	6% 4 2 4 3 4 5% 4 6% 10% 51%	2677
July	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 46%	5900
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 6% 10% 46%	5900
	21st to end	Day	6% 5% 2 5% 4 5% 5% 5% 7% 10% 46%	6422
August	1st to 10th	Day	5% 4 2 5% 4 4 4 4 6% 8% 53%	4234
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 6% 7% 48%	4171
	21st to end	Day	6% 3 2 5% 3 4 4 3 5% 9% 55%	4454
September	1st to 10th	Day	12% 4 2 4 3 3 3 3 5% 7% 53%	2369
	11th to 20th	Day	8% 6% 3 6% 4 4 4 4 6% 7% 49%	2200
	21st to end	Day	8% 5% 1 6% 4 3 4 4 6% 5% 54%	2200
October	1st to 10th	Day	11% 5% 1 5% 4 2 3 3 5% 6% 54%	2014
	11th to 20th	Day	11% 6% 2 5% 3 3 2 2 4 5% 57%	2000
	21st to end	Day	17% 6% 2 5% 3 3 3 3 4 6% 49%	2200
November	1st to 10th	Day	9% 5% 2 5% 3 3 3 3 5% 6% 56%	2016
	11th to 20th	Day	12% 6% 2 4 3 4 4 3 4 6% 54%	1854
	21st to end	Day	15% 8% 2 5% 3 2 2 3 4 5% 49%	1600
December	1st to 10th	Day	6% 5% 2 4 4 4 4 3 5% 6% 58%	2610
	11th to 20th	Day	10% 7% 3 7% 4 3 4 2 4 5% 50%	3008
	21st to end	Day	18% 16% 7% 10% 4 3 3 3 3 6% 26%	4332
January	1st to 10th	Night	12% 10% 4 13% 5% 4 4 3 4 5% 36%	5888
	11th to 20th	Night	8% 9% 3 9% 5% 5% 5% 3 4 5% 45%	5900
	21st to end	Night	14% 9% 4 9% 4 3 4 3 4 6% 41%	6490
February	1st to 10th	Night	10% 12% 3 8% 5% 4 4 3 5% 6% 40%	2600
	11th to 20th	Night	11% 9% 3 6% 4 5% 4 3 5% 6% 43%	2528
	21st to end	Night	11% 7% 3 6% 4 4 5% 3 4 5% 48%	1935
March	1st to 10th	Night	14% 7% 2 4 3 3 3 2 4 4 54%	4919
	11th to 20th	Night	8% 5% 2 4 2 3 3 3 5% 8% 58%	4980
	21st to end	Night	14% 8% 2 7% 4 4 4 4 5% 7% 39%	5467
April	1st to 10th	Night	11% 6% 2 5% 4 3 4 3 5% 6% 50%	2118
	11th to 20th	Night	12% 8% 2 6% 4 4 3 3 4 7% 47%	1975
	21st to end	Night	17% 7% 2 6% 4 4 5% 3 5% 6% 41%	1810
May	1st to 10th	Night	15% 8% 2 5% 4 3 3 3 6% 7% 44%	4053
	11th to 20th	Night	13% 6% 2 5% 3 3 3 3 4 7% 51%	4053
	21st to end	Night	16% 5% 2 4 3 3 3 2 5% 6% 51%	4443
June	1st to 10th	Night	6% 3 1 4 4 5% 4 4 6% 8% 56%	1640
	11th to 20th	Night	5% 4 1 4 4 4 5% 4 7% 10% 52%	1600
	21st to end	Night	4 3 1 4 3 2 4 4 5% 9% 60%	1713
July	1st to 10th	Night	8% 5% 2 5% 4 4 4 4 5% 8% 52%	4078
	11th to 20th	Night	4 4 2 4 4 4 4 4 6% 10% 54%	4077
	21st to end	Night	7% 4 2 6% 4 4 5% 4 7% 10% 47%	4449
August	1st to 10th	Night	2 2 1 3 3 4 4 4 8% 10% 59%	2926
	11th to 20th	Night	10% 5% 2 5% 4 4 3 3 5% 7% 52%	2888
	21st to end	Night	4 4 2 5% 4 3 3 3 6% 7% 59%	3448
September	1st to 10th	Night	10% 5% 1 5% 3 3 3 4 4 6% 56%	2028
	11th to 20th	Night	8% 4 2 4 3 4 4 5% 5% 7% 54%	2200
	21st to end	Night	6% 4 2 5% 4 3 4 3 4 6% 59%	2200
October	1st to 10th	Night	11% 4 1 4 3 3 4 3 5% 5% 57%	2365
	11th to 20th	Night	12% 5% 1 4 2 3 3 2 4 6% 57%	2400
	21st to end	Night	15% 7% 2 5% 3 3 3 2 3 4 52%	2640
November	1st to 10th	Night	9% 5% 1 4 2 3 3 2 4 6% 61%	2497
	11th to 20th	Night	9% 5% 2 4 3 3 4 3 5% 6% 55%	2697
	21st to end	Night	14% 7% 2 4 2 2 4 2 4 6% 53%	2800
December	1st to 10th	Night	6% 6% 2 5% 4 3 4 3 5% 6% 58%	4580
	11th to 20th	Night	11% 7% 3 6% 3 4 4 3 5% 6% 47%	5199
	21st to end	Night	19% 15% 5% 8% 4 4 4 2 4 4 32%	6628

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	48% 5% 10% 25% 11% 1	4078
	11th to 20th	Day	46% 4 11% 21% 15% 4	4080
	21st to end	Day	48% 4 12% 17% 18% 2	4488
February	1st to 10th	Day	48% 4 13% 23% 10% 3	1800
	11th to 20th	Day	45% 4 11% 23% 15% 2	1783
	21st to end	Day	38% 4 11% 26% 17% 4	1693
March	1st to 10th	Day	35% 3 10% 21% 23% 9%	4936
	11th to 20th	Day	29% 4 9% 22% 28% 7%	4980
	21st to end	Day	46% 6% 14% 27% 6% 1	5464
April	1st to 10th	Day	39% 5% 12% 22% 19% 3	2280
	11th to 20th	Day	43% 5% 12% 22% 17% 1	2374
	21st to end	Day	49% 6% 11% 23% 11% 1	2586
May	1st to 10th	Day	40% 6% 10% 26% 17% 1	5900
	11th to 20th	Day	35% 7% 11% 24% 20% 4	5866
	21st to end	Day	42% 6% 10% 27% 13% 1	6447
June	1st to 10th	Day	27% 9% 17% 28% 17% 2	2755
	11th to 20th	Day	30% 9% 14% 29% 17% 2	2800
	21st to end	Day	28% 7% 16% 28% 17% 4	2677
July	1st to 10th	Day	33% 7% 13% 27% 19% 2	5836
	11th to 20th	Day	31% 7% 13% 29% 17% 2	5831
	21st to end	Day	30% 8% 15% 33% 12% 2	6240
August	1st to 10th	Day	28% 7% 14% 28% 21% 3	4220
	11th to 20th	Day	34% 6% 16% 27% 16% 1	4210
	21st to end	Day	26% 6% 16% 31% 15% 6%	4453
September	1st to 10th	Day	31% 5% 12% 26% 20% 6%	2369
	11th to 20th	Day	33% 7% 11% 27% 20% 3	2200
	21st to end	Day	30% 6% 9% 28% 25% 3	2200
October	1st to 10th	Day	19% 3 7% 23% 41% 7%	3274
	11th to 20th	Day	19% 3 5% 28% 36% 10%	3240
	21st to end	Day	31% 4 11% 25% 25% 3	3538
November	1st to 10th	Day	29% 5% 13% 30% 18% 5%	2016
	11th to 20th	Day	32% 4 9% 30% 21% 4	1854
	21st to end	Day	39% 3 9% 26% 21% 1	1600
December	1st to 10th	Day	28% 5% 12% 38% 16% 1	2610
	11th to 20th	Day	38% 5% 12% 33% 12% 1	3005
	21st to end	Day	61% 4 10% 17% 7% 1	4332
January	1st to 10th	Night	50% 5% 12% 22% 10% 1	5888
	11th to 20th	Night	42% 4 10% 23% 17% 3	5900
	21st to end	Night	45% 4 11% 18% 17% 5%	6490
February	1st to 10th	Night	46% 4 12% 21% 14% 3	2600
	11th to 20th	Night	42% 4 12% 23% 16% 3	2529
	21st to end	Night	37% 4 9% 21% 21% 7%	1935
March	1st to 10th	Night	35% 4 7% 24% 26% 4	4919
	11th to 20th	Night	26% 4 8% 21% 33% 8%	4980
	21st to end	Night	42% 7% 15% 25% 9% 2	5467
April	1st to 10th	Night	35% 5% 11% 23% 21% 4	2118
	11th to 20th	Night	38% 4 10% 27% 18% 4	1975
	21st to end	Night	42% 6% 12% 24% 14% 1	1810
May	1st to 10th	Night	37% 7% 13% 24% 16% 2	4080
	11th to 20th	Night	34% 5% 10% 25% 19% 6%	4054
	21st to end	Night	34% 6% 11% 29% 19% 1	4452
June	1st to 10th	Night	24% 9% 17% 31% 16% 3	1640
	11th to 20th	Night	25% 8% 14% 32% 19% 3	1600
	21st to end	Night	19% 6% 15% 34% 21% 4	1713
July	1st to 10th	Night	30% 7% 13% 24% 23% 3	4035
	11th to 20th	Night	25% 7% 15% 31% 20% 2	4026
	21st to end	Night	28% 7% 16% 34% 13% 1	4320
August	1st to 10th	Night	17% 8% 19% 29% 21% 6%	2916
	11th to 20th	Night	32% 6% 13% 28% 19% 2	2915
	21st to end	Night	23% 5% 13% 37% 17% 5%	3448
September	1st to 10th	Night	30% 6% 10% 26% 21% 8%	2028
	11th to 20th	Night	27% 7% 12% 26% 24% 4	2200
	21st to end	Night	26% 6% 9% 25% 30% 4	2200
October	1st to 10th	Night	19% 4 6% 18% 47% 6%	3872
	11th to 20th	Night	21% 2 6% 27% 30% 13%	3899
	21st to end	Night	33% 3 7% 29% 25% 3	4252
November	1st to 10th	Night	27% 3 12% 28% 24% 6%	2497
	11th to 20th	Night	30% 4 10% 28% 23% 5%	2697
	21st to end	Night	34% 4 10% 30% 19% 3	2800
December	1st to 10th	Night	28% 5% 13% 34% 19% 1	4580
	11th to 20th	Night	38% 3 13% 28% 15% 3	5201
	21st to end	Night	57% 5% 10% 21% 7% 1	6628

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	21% 16% 34% 24% 5%	300
	11th to 20th	Day	22% 19% 41% 16% 3	300
	21st to end	Day	13% 11% 49% 22% 4	330
February	1st to 10th	Day	20% 22% 38% 18% 1 1	300
	11th to 20th	Day	21% 18% 43% 12% 6%	300
	21st to end	Day	14% 26% 41% 17% 2	249
March	1st to 10th	Day	14% 17% 45% 20% 4	300
	11th to 20th	Day	26% 14% 34% 20% 5%	300
	21st to end	Day	30% 18% 36% 13% 3 1	330
April	1st to 10th	Day	23% 17% 34% 20% 7%	380
	11th to 20th	Day	18% 16% 37% 22% 5% 1	492
	21st to end	Day	23% 14% 35% 19% 9% 1	686
May	1st to 10th	Day	17% 15% 34% 23% 10% 1	703
	11th to 20th	Day	18% 10% 28% 29% 13% 2	725
	21st to end	Day	17% 9% 29% 27% 15% 3	789
June	1st to 10th	Day	5% 6% 22% 35% 26% 7%	730
	11th to 20th	Day	7% 3 28% 37% 20% 5%	730
	21st to end	Day	7% 6% 33% 37% 16% 2	730
July	1st to 10th	Day	8% 4 15% 31% 31% 10%	721
	11th to 20th	Day	5% 2 20% 36% 29% 9%	718
	21st to end	Day	8% 2 16% 35% 30% 9%	794
August	1st to 10th	Day	6% 2 19% 40% 28% 5%	726
	11th to 20th	Day	8% 4 15% 40% 27% 6%	715
	21st to end	Day	8% 1 15% 33% 33% 9%	673
September	1st to 10th	Day	12% 2 18% 34% 28% 6%	499
	11th to 20th	Day	5% 3 23% 37% 26% 6%	330
	21st to end	Day	13% 5% 25% 34% 16% 6%	330
October	1st to 10th	Day	14% 7% 28% 27% 17% 7%	330
	11th to 20th	Day	11% 17% 38% 24% 9% 1	330
	21st to end	Day	24% 14% 35% 18% 8% 1	363
November	1st to 10th	Day	15% 15% 39% 22% 7% 3	330
	11th to 20th	Day	15% 19% 33% 23% 8% 1	321
	21st to end	Day	22% 15% 35% 20% 9%	300
December	1st to 10th	Day	8% 16% 41% 28% 5% 3	300
	11th to 20th	Day	17% 16% 38% 21% 6% 1	300
	21st to end	Day	23% 20% 37% 17% 2	330
January	1st to 10th	Night	13% 13% 37% 30% 7%	1000
	11th to 20th	Night	15% 13% 38% 27% 6% 1	1000
	21st to end	Night	14% 13% 40% 29% 4	1100
February	1st to 10th	Night	18% 13% 40% 26% 3	1000
	11th to 20th	Night	16% 14% 39% 27% 3	974
	21st to end	Night	17% 12% 40% 26% 5%	615
March	1st to 10th	Night	15% 12% 43% 25% 5%	600
	11th to 20th	Night	18% 12% 38% 27% 5% 1	600
	21st to end	Night	23% 14% 36% 23% 4	660
April	1st to 10th	Night	15% 11% 40% 28% 5% 1	600
	11th to 20th	Night	16% 15% 35% 30% 5%	593
	21st to end	Night	19% 11% 37% 26% 8% 1	600
May	1st to 10th	Night	17% 8% 32% 35% 8% 1	600
	11th to 20th	Night	15% 6% 30% 34% 14%	591
	21st to end	Night	12% 6% 29% 35% 16% 2	650
June	1st to 10th	Night	6% 4 22% 43% 25% 1	600
	11th to 20th	Night	6% 3 28% 44% 17% 2	600
	21st to end	Night	5% 4 30% 47% 14% 1	600
July	1st to 10th	Night	8% 2 14% 44% 31% 2	585
	11th to 20th	Night	2 2 16% 49% 28% 2	582
	21st to end	Night	8% 2 15% 47% 27% 1	657
August	1st to 10th	Night	4 2 16% 50% 27% 1	597
	11th to 20th	Night	7% 2 12% 45% 30% 3	594
	21st to end	Night	7% 1 13% 42% 35% 2	660
September	1st to 10th	Night	13% 3 18% 42% 23% 2	600
	11th to 20th	Night	8% 3 22% 41% 24% 2	600
	21st to end	Night	7% 4 24% 43% 21% 2	600
October	1st to 10th	Night	12% 4 29% 33% 21% 1	765
	11th to 20th	Night	15% 9% 37% 31% 9%	800
	21st to end	Night	19% 12% 34% 27% 8%	880
November	1st to 10th	Night	11% 11% 33% 34% 11% 1	857
	11th to 20th	Night	12% 15% 37% 28% 8%	1036
	21st to end	Night	18% 11% 35% 30% 7%	1000
December	1st to 10th	Night	14% 13% 35% 32% 6% 1	1000
	11th to 20th	Night	18% 10% 39% 28% 5%	1000
	21st to end	Night	20% 13% 35% 27% 4	1100

Page generated at 2025-11-14 23:55:58. Version ac07

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