Lamoine Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lamoine Observatory clear sky chart from 2005-11-06 to 2026-02-01.

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	19% 9% 3 6% 4 4 4 3 5% 7% 37%	126963
	Night	19% 9% 3 6% 4 4 4 3 5% 6% 36%	125095
Transparency	Day	46% 6% 12% 22% 13% 2	130485
	Night	48% 5% 11% 21% 13% 2	129662
Seeing	Day	23% 15% 32% 21% 7% 1	17408
	Night	24% 15% 29% 23% 7% 1	25814

By Month

Percentage Cloud Cover NE (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% 10% 3 7% 5% 5% 5% 4 5% 6% 36%	3673
	11th to 20th	Day	14% 10% 3 6% 4 4 5% 3 4 5% 42%	3650
	21st to end	Day	13% 10% 3 7% 4 4 3 3 5% 6% 42%	4215
February	1st to 10th	Day	16% 12% 3 7% 4 5% 4 4 6% 7% 33%	1800
	11th to 20th	Day	14% 9% 2 7% 4 5% 5% 4 6% 6% 37%	1842
	21st to end	Day	13% 10% 3 8% 5% 4 5% 4 5% 6% 36%	1650
March	1st to 10th	Day	25% 11% 3 6% 4 5% 4 3 4 5% 30%	4559
	11th to 20th	Day	22% 10% 2 6% 4 4 4 3 4 6% 34%	4980
	21st to end	Day	29% 9% 3 6% 4 4 3 3 4 5% 30%	5466
April	1st to 10th	Day	21% 11% 3 6% 4 4 4 3 4 6% 34%	2347
	11th to 20th	Day	20% 8% 3 6% 4 3 4 3 4 7% 38%	2565
	21st to end	Day	21% 9% 2 5% 3 4 4 3 4 7% 37%	2600
May	1st to 10th	Day	29% 12% 3 7% 4 4 3 3 4 6% 26%	5886
	11th to 20th	Day	19% 9% 3 8% 4 4 4 3 5% 6% 34%	5861
	21st to end	Day	20% 8% 3 6% 4 4 5% 4 6% 7% 32%	7074
June	1st to 10th	Day	22% 9% 3 6% 5% 3 4 4 5% 8% 32%	3000
	11th to 20th	Day	18% 8% 3 5% 4 4 4 3 4 8% 39%	3000
	21st to end	Day	25% 8% 2 6% 4 4 4 4 5% 7% 31%	3000
July	1st to 10th	Day	18% 9% 2 7% 4 4 5% 3 7% 8% 32%	6621
	11th to 20th	Day	18% 10% 3 6% 3 3 4 3 5% 8% 38%	6360
	21st to end	Day	16% 6% 2 5% 3 4 4 3 6% 8% 43%	6745
August	1st to 10th	Day	19% 8% 3 6% 4 4 4 3 5% 8% 36%	4235
	11th to 20th	Day	17% 8% 2 7% 4 5% 4 3 6% 7% 36%	4175
	21st to end	Day	10% 5% 2 5% 4 3 3 4 6% 9% 50%	4675
September	1st to 10th	Day	12% 5% 2 5% 3 4 4 4 5% 8% 49%	2300
	11th to 20th	Day	13% 5% 2 4 3 4 4 3 4 6% 53%	2200
	21st to end	Day	17% 6% 2 5% 3 4 3 4 4 6% 44%	2200
October	1st to 10th	Day	17% 7% 3 6% 3 4 5% 4 5% 6% 43%	2126
	11th to 20th	Day	18% 6% 2 6% 4 4 3 3 5% 6% 42%	2000
	21st to end	Day	22% 8% 3 5% 4 4 4 3 5% 6% 39%	1995
November	1st to 10th	Day	18% 7% 2 7% 4 3 4 3 5% 6% 41%	1851
	11th to 20th	Day	21% 5% 2 5% 3 3 4 3 5% 7% 42%	1822
	21st to end	Day	19% 10% 3 6% 4 3 3 3 5% 5% 40%	1680
December	1st to 10th	Day	18% 10% 2 4 3 3 4 3 4 6% 43%	2569
	11th to 20th	Day	21% 9% 2 5% 3 3 3 3 4 5% 41%	2688
	21st to end	Day	20% 12% 4 6% 3 3 2 3 4 5% 38%	3553
January	1st to 10th	Night	13% 10% 4 7% 5% 4 4 3 5% 7% 40%	6489
	11th to 20th	Night	15% 11% 4 9% 5% 4 5% 3 5% 6% 34%	6455
	21st to end	Night	12% 10% 3 7% 5% 4 4 4 5% 7% 40%	6980
February	1st to 10th	Night	18% 11% 3 7% 4 4 5% 3 5% 6% 34%	2601
	11th to 20th	Night	14% 9% 3 7% 5% 4 4 3 5% 6% 39%	2443
	21st to end	Night	15% 10% 3 7% 5% 4 4 3 5% 6% 39%	1980
March	1st to 10th	Night	27% 11% 3 7% 5% 3 3 2 4 5% 31%	5279
	11th to 20th	Night	17% 11% 3 6% 4 5% 5% 4 6% 6% 31%	4979
	21st to end	Night	27% 9% 2 6% 4 4 4 4 6% 6% 29%	5466
April	1st to 10th	Night	23% 11% 2 6% 4 4 3 4 4 5% 33%	2050
	11th to 20th	Night	21% 8% 3 7% 5% 4 3 3 5% 7% 35%	1783
	21st to end	Night	24% 9% 3 7% 4 3 3 3 4 6% 34%	1800
May	1st to 10th	Night	29% 11% 3 7% 4 3 4 3 4 6% 26%	4054
	11th to 20th	Night	24% 9% 2 6% 5% 4 4 4 6% 7% 30%	4033
	21st to end	Night	16% 12% 4 9% 5% 4 4 3 5% 6% 32%	3838
June	1st to 10th	Night	24% 10% 3 6% 4 4 4 4 6% 7% 28%	1400
	11th to 20th	Night	19% 9% 3 6% 3 3 4 3 6% 7% 36%	1400
	21st to end	Night	26% 11% 2 5% 4 5% 4 3 5% 6% 30%	1400
July	1st to 10th	Night	18% 10% 3 8% 6% 4 5% 4 7% 8% 27%	3333
	11th to 20th	Night	21% 13% 3 6% 4 4 4 4 6% 7% 30%	3600
	21st to end	Night	14% 7% 2 6% 3 4 5% 4 6% 9% 39%	4062
August	1st to 10th	Night	23% 10% 3 7% 4 5% 5% 4 5% 6% 29%	2915
	11th to 20th	Night	19% 9% 3 7% 4 4 5% 5% 6% 8% 30%	2872
	21st to end	Night	10% 6% 2 6% 4 4 4 3 6% 9% 45%	3223
September	1st to 10th	Night	14% 5% 2 4 4 3 4 3 6% 7% 48%	2097
	11th to 20th	Night	15% 6% 2 4 3 3 3 3 4 7% 49%	2200
	21st to end	Night	18% 7% 2 5% 3 3 4 3 5% 8% 44%	2200
October	1st to 10th	Night	19% 6% 2 5% 4 4 3 3 5% 7% 43%	2273
	11th to 20th	Night	19% 7% 2 6% 3 4 4 3 4 7% 42%	2400
	21st to end	Night	23% 9% 3 5% 4 4 3 3 4 6% 37%	2841
November	1st to 10th	Night	18% 6% 2 5% 4 3 5% 3 5% 6% 42%	2667
	11th to 20th	Night	17% 7% 2 6% 4 4 4 3 5% 6% 41%	2796
	21st to end	Night	18% 9% 3 5% 4 4 4 4 5% 6% 39%	2940
December	1st to 10th	Night	18% 9% 2 5% 4 4 4 4 6% 6% 38%	4838
	11th to 20th	Night	23% 8% 2 5% 3 2 2 3 4 6% 42%	5741
	21st to end	Night	22% 10% 3 5% 4 3 3 3 5% 6% 37%	7667

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	49% 4 12% 26% 8%	3674
	11th to 20th	Day	44% 5% 12% 25% 12% 2	3680
	21st to end	Day	43% 4 11% 19% 17% 5%	4215
February	1st to 10th	Day	52% 5% 12% 17% 11% 3	1800
	11th to 20th	Day	48% 5% 14% 19% 13% 2	1850
	21st to end	Day	48% 5% 11% 21% 11% 4	1650
March	1st to 10th	Day	55% 4 9% 11% 15% 6%	4563
	11th to 20th	Day	49% 5% 16% 19% 10% 1	4980
	21st to end	Day	56% 3 6% 16% 16% 3	5466
April	1st to 10th	Day	51% 5% 9% 17% 15% 3	2347
	11th to 20th	Day	45% 5% 10% 23% 13% 3	2565
	21st to end	Day	47% 5% 9% 19% 16% 3	2600
May	1st to 10th	Day	59% 7% 11% 16% 6% 1	5897
	11th to 20th	Day	50% 6% 12% 22% 7% 2	5865
	21st to end	Day	50% 7% 12% 19% 11% 1	7074
June	1st to 10th	Day	51% 7% 12% 20% 10%	3000
	11th to 20th	Day	45% 6% 12% 21% 15% 2	3000
	21st to end	Day	53% 6% 10% 18% 11% 2	3000
July	1st to 10th	Day	49% 7% 12% 21% 10%	6550
	11th to 20th	Day	45% 6% 13% 22% 13% 1	6285
	21st to end	Day	38% 6% 13% 27% 15% 1	6551
August	1st to 10th	Day	47% 7% 13% 24% 8%	4222
	11th to 20th	Day	46% 6% 17% 20% 9%	4214
	21st to end	Day	30% 7% 13% 29% 21% 1	4675
September	1st to 10th	Day	34% 7% 13% 27% 18% 1	2300
	11th to 20th	Day	33% 6% 12% 27% 20% 3	2200
	21st to end	Day	41% 6% 9% 26% 17% 1	2200
October	1st to 10th	Day	45% 7% 11% 24% 12% 1	3464
	11th to 20th	Day	32% 3 10% 34% 21%	3240
	21st to end	Day	34% 5% 17% 24% 18% 3	3195
November	1st to 10th	Day	43% 5% 13% 23% 13% 1	1851
	11th to 20th	Day	42% 6% 9% 23% 17% 3	1822
	21st to end	Day	48% 5% 15% 23% 8% 1	1680
December	1st to 10th	Day	44% 4 15% 23% 13% 1	2569
	11th to 20th	Day	47% 3 12% 18% 14% 5%	2688
	21st to end	Day	50% 5% 11% 19% 12% 3	3553
January	1st to 10th	Night	45% 4 13% 27% 10% 1	6489
	11th to 20th	Night	51% 5% 12% 21% 9% 1	6500
	21st to end	Night	44% 4 10% 22% 16% 4	6980
February	1st to 10th	Night	52% 5% 12% 18% 12% 2	2601
	11th to 20th	Night	47% 5% 12% 19% 15% 3	2446
	21st to end	Night	48% 4 10% 21% 14% 4	1980
March	1st to 10th	Night	58% 2 7% 12% 13% 8%	5288
	11th to 20th	Night	49% 7% 21% 15% 8% 1	4980
	21st to end	Night	56% 3 6% 17% 16% 2	5466
April	1st to 10th	Night	52% 5% 9% 14% 16% 3	2050
	11th to 20th	Night	49% 5% 9% 20% 15% 2	1783
	21st to end	Night	52% 5% 9% 17% 14% 3	1800
May	1st to 10th	Night	60% 5% 12% 15% 8% 1	4060
	11th to 20th	Night	52% 7% 13% 19% 8% 1	4034
	21st to end	Night	52% 6% 12% 20% 10%	3839
June	1st to 10th	Night	54% 7% 10% 19% 8% 1	1400
	11th to 20th	Night	47% 8% 11% 21% 11% 2	1400
	21st to end	Night	55% 5% 9% 19% 10% 2	1400
July	1st to 10th	Night	55% 7% 10% 20% 8%	3295
	11th to 20th	Night	53% 7% 11% 19% 10%	3552
	21st to end	Night	41% 7% 16% 24% 11% 1	3942
August	1st to 10th	Night	56% 6% 11% 20% 7%	2903
	11th to 20th	Night	49% 7% 13% 21% 9%	2899
	21st to end	Night	37% 6% 11% 25% 21% 1	3223
September	1st to 10th	Night	36% 6% 12% 29% 17% 1	2097
	11th to 20th	Night	36% 4 11% 26% 20% 2	2200
	21st to end	Night	39% 4 11% 27% 17% 1	2200
October	1st to 10th	Night	41% 4 13% 25% 15% 1	3715
	11th to 20th	Night	34% 4 10% 29% 23% 1	3899
	21st to end	Night	40% 3 10% 30% 15% 3	4591
November	1st to 10th	Night	43% 5% 12% 24% 15% 1	2667
	11th to 20th	Night	44% 5% 11% 22% 15% 2	2796
	21st to end	Night	46% 6% 14% 20% 12% 2	2940
December	1st to 10th	Night	47% 5% 10% 27% 12%	4838
	11th to 20th	Night	45% 3 12% 21% 16% 2	5742
	21st to end	Night	50% 4 11% 18% 15% 1	7667

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	25% 30% 32% 11% 3	220
	11th to 20th	Day	29% 26% 31% 10% 3	220
	21st to end	Day	18% 27% 35% 18% 3	318
February	1st to 10th	Day	25% 27% 31% 15% 2	400
	11th to 20th	Day	27% 29% 33% 9% 2	441
	21st to end	Day	23% 22% 36% 16% 3	414
March	1st to 10th	Day	27% 25% 31% 14% 2	500
	11th to 20th	Day	24% 24% 33% 16% 3	500
	21st to end	Day	29% 23% 29% 14% 5% 1	550
April	1st to 10th	Day	30% 22% 32% 12% 3 1	500
	11th to 20th	Day	27% 18% 37% 12% 4 1	492
	21st to end	Day	25% 16% 35% 18% 4 1	500
May	1st to 10th	Day	28% 19% 33% 15% 4 1	503
	11th to 20th	Day	18% 18% 34% 23% 6% 1	527
	21st to end	Day	26% 12% 35% 19% 8% 1	694
June	1st to 10th	Day	25% 9% 32% 24% 9% 2	730
	11th to 20th	Day	24% 9% 31% 24% 11% 1	730
	21st to end	Day	29% 6% 29% 26% 9% 1	730
July	1st to 10th	Day	23% 7% 33% 24% 12% 1	642
	11th to 20th	Day	22% 4 32% 30% 11% 1	524
	21st to end	Day	16% 6% 35% 31% 10% 1	576
August	1st to 10th	Day	15% 6% 29% 34% 13% 2	526
	11th to 20th	Day	19% 5% 29% 29% 14% 4	519
	21st to end	Day	16% 7% 30% 32% 12% 3	583
September	1st to 10th	Day	18% 5% 33% 32% 11% 2	530
	11th to 20th	Day	18% 9% 29% 25% 12% 6%	530
	21st to end	Day	18% 9% 33% 25% 12% 4	530
October	1st to 10th	Day	18% 14% 26% 29% 13% 1	489
	11th to 20th	Day	19% 17% 31% 23% 8% 1	420
	21st to end	Day	28% 16% 32% 18% 5% 1	462
November	1st to 10th	Day	22% 20% 31% 20% 6% 1	425
	11th to 20th	Day	24% 22% 33% 16% 3 1	430
	21st to end	Day	29% 24% 28% 16% 3	430
December	1st to 10th	Day	26% 21% 32% 17% 3	361
	11th to 20th	Day	30% 30% 28% 10% 1	220
	21st to end	Day	29% 28% 24% 15% 4	242
January	1st to 10th	Night	23% 26% 32% 17% 2	840
	11th to 20th	Night	28% 22% 32% 14% 4	840
	21st to end	Night	18% 30% 33% 16% 3	924
February	1st to 10th	Night	25% 25% 33% 13% 3	801
	11th to 20th	Night	23% 30% 32% 13% 2 1	783
	21st to end	Night	22% 21% 34% 19% 4	660
March	1st to 10th	Night	25% 21% 35% 18% 2	800
	11th to 20th	Night	23% 19% 31% 21% 6%	800
	21st to end	Night	25% 18% 33% 19% 6% 1	880
April	1st to 10th	Night	31% 16% 32% 18% 3	800
	11th to 20th	Night	27% 10% 35% 25% 4	599
	21st to end	Night	30% 11% 29% 22% 7% 1	600
May	1st to 10th	Night	28% 8% 30% 26% 7% 1	600
	11th to 20th	Night	25% 8% 33% 27% 7%	592
	21st to end	Night	25% 6% 27% 31% 10% 1	521
June	1st to 10th	Night	31% 6% 24% 30% 9% 1	400
	11th to 20th	Night	25% 4 25% 33% 13% 1	400
	21st to end	Night	34% 2 19% 34% 10% 1	400
July	1st to 10th	Night	24% 3 24% 36% 12%	390
	11th to 20th	Night	25% 2 21% 36% 14% 1	388
	21st to end	Night	23% 2 21% 40% 13% 1	498
August	1st to 10th	Night	22% 3 21% 39% 14% 1	598
	11th to 20th	Night	22% 3 20% 40% 14% 2	592
	21st to end	Night	17% 4 23% 36% 19% 2	660
September	1st to 10th	Night	17% 3 28% 35% 16% 2	777
	11th to 20th	Night	20% 6% 24% 29% 17% 4	800
	21st to end	Night	20% 6% 28% 30% 14% 2	800
October	1st to 10th	Night	22% 9% 26% 27% 16% 1	800
	11th to 20th	Night	22% 14% 28% 23% 12% 1	800
	21st to end	Night	28% 16% 30% 21% 5%	880
November	1st to 10th	Night	23% 17% 30% 23% 7% 1	820
	11th to 20th	Night	22% 23% 29% 20% 6% 1	876
	21st to end	Night	26% 23% 31% 15% 5% 1	950
December	1st to 10th	Night	30% 19% 33% 15% 3	950
	11th to 20th	Night	28% 27% 29% 14% 2	950
	21st to end	Night	29% 22% 30% 16% 3	1045

Page generated at 2026-01-29 01:21:46. Version ac07

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