Livonia
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Livonia clear sky chart from 2005-11-06 to 2025-10-19.

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	14% 10% 3 8% 5% 5% 5% 4 6% 7% 33%	125817
	Night	15% 11% 4 8% 5% 4 4 4 5% 6% 34%	123976
Transparency	Day	48% 6% 12% 21% 12% 1	129401
	Night	48% 6% 11% 21% 13% 1	128462
Seeing	Day	18% 13% 30% 22% 12% 4	16722
	Night	20% 11% 29% 28% 11% 1	26532

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	11% 16% 6% 16% 6% 5% 3 3 4 5% 23%	3617
	11th to 20th	Day	14% 15% 7% 18% 8% 8% 7% 3 4 5% 10%	3620
	21st to end	Day	21% 17% 6% 13% 7% 5% 5% 3 4 5% 14%	4439
February	1st to 10th	Day	15% 15% 4 13% 8% 6% 5% 4 5% 5% 21%	1800
	11th to 20th	Day	14% 14% 4 12% 8% 6% 5% 3 5% 6% 23%	1892
	21st to end	Day	15% 15% 5% 11% 5% 4 4 4 5% 7% 25%	1650
March	1st to 10th	Day	16% 13% 5% 11% 6% 4 4 3 4 5% 29%	4606
	11th to 20th	Day	13% 11% 4 9% 5% 4 5% 3 5% 8% 34%	4980
	21st to end	Day	18% 15% 4 9% 6% 4 4 3 4 5% 28%	5465
April	1st to 10th	Day	16% 13% 3 7% 5% 5% 5% 4 5% 7% 30%	2320
	11th to 20th	Day	17% 10% 3 7% 5% 4 5% 3 4 7% 35%	2537
	21st to end	Day	18% 9% 3 7% 5% 5% 4 3 5% 7% 35%	2600
May	1st to 10th	Day	19% 10% 3 7% 4 5% 4 3 5% 6% 33%	5862
	11th to 20th	Day	17% 7% 3 7% 5% 5% 5% 5% 6% 8% 32%	5861
	21st to end	Day	14% 6% 2 7% 4 4 5% 3 5% 7% 41%	6433
June	1st to 10th	Day	10% 6% 3 7% 6% 5% 5% 4 6% 9% 40%	2776
	11th to 20th	Day	11% 5% 3 7% 4 6% 5% 5% 7% 9% 39%	2964
	21st to end	Day	9% 6% 3 6% 5% 5% 6% 5% 8% 9% 38%	2800
July	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 4 7% 10% 40%	6360
	11th to 20th	Day	6% 5% 2 6% 5% 5% 5% 5% 7% 10% 44%	6360
	21st to end	Day	7% 6% 2 6% 5% 4 5% 4 7% 10% 44%	6497
August	1st to 10th	Day	10% 6% 2 6% 4 5% 5% 5% 7% 8% 42%	4234
	11th to 20th	Day	10% 5% 3 7% 6% 5% 6% 5% 9% 9% 35%	4174
	21st to end	Day	8% 5% 2 7% 5% 6% 6% 5% 7% 10% 38%	4623
September	1st to 10th	Day	10% 6% 2 6% 5% 5% 6% 5% 7% 8% 40%	2256
	11th to 20th	Day	8% 5% 1 5% 5% 4 6% 4 7% 9% 47%	2200
	21st to end	Day	15% 7% 2 8% 5% 4 5% 4 6% 8% 37%	2200
October	1st to 10th	Day	12% 7% 3 6% 4 4 4 4 6% 8% 42%	2145
	11th to 20th	Day	16% 9% 2 7% 5% 5% 5% 4 6% 6% 34%	1980
	21st to end	Day	19% 10% 3 8% 5% 5% 4 4 5% 7% 31%	1943
November	1st to 10th	Day	11% 9% 3 8% 5% 5% 4 4 6% 6% 38%	1762
	11th to 20th	Day	15% 12% 4 8% 6% 5% 5% 3 6% 6% 30%	1800
	21st to end	Day	18% 13% 4 9% 5% 5% 4 4 4 7% 26%	1709
December	1st to 10th	Day	14% 12% 7% 16% 7% 6% 5% 3 5% 6% 21%	2600
	11th to 20th	Day	20% 19% 6% 9% 6% 5% 4 3 5% 5% 18%	2793
	21st to end	Day	27% 20% 7% 12% 5% 4 3 3 3 4 13%	3959
January	1st to 10th	Night	14% 15% 6% 12% 6% 4 4 3 5% 6% 25%	6348
	11th to 20th	Night	12% 16% 7% 15% 8% 5% 6% 5% 5% 5% 15%	6360
	21st to end	Night	18% 17% 8% 11% 5% 5% 4 3 4 5% 22%	6514
February	1st to 10th	Night	16% 15% 5% 11% 7% 4 5% 4 4 5% 23%	2600
	11th to 20th	Night	15% 12% 5% 11% 7% 5% 4 4 5% 6% 27%	2392
	21st to end	Night	19% 12% 4 9% 5% 5% 4 3 5% 6% 28%	1980
March	1st to 10th	Night	15% 12% 4 8% 5% 4 4 3 5% 6% 34%	5246
	11th to 20th	Night	10% 8% 3 6% 4 4 5% 4 6% 8% 41%	4980
	21st to end	Night	17% 10% 3 8% 5% 5% 4 3 5% 6% 36%	5467
April	1st to 10th	Night	16% 10% 4 6% 4 4 4 3 5% 7% 35%	2096
	11th to 20th	Night	17% 8% 3 7% 4 4 4 4 7% 6% 37%	1812
	21st to end	Night	16% 8% 2 6% 5% 4 5% 4 4 6% 39%	1800
May	1st to 10th	Night	20% 10% 3 8% 5% 4 4 3 5% 5% 32%	4033
	11th to 20th	Night	18% 8% 3 7% 4 4 4 3 4 6% 38%	4032
	21st to end	Night	13% 6% 2 6% 4 4 4 3 6% 8% 44%	4421
June	1st to 10th	Night	12% 6% 2 4 3 4 4 3 5% 10% 46%	1601
	11th to 20th	Night	10% 4 2 7% 4 5% 5% 4 6% 9% 44%	1416
	21st to end	Night	10% 4 2 6% 4 4 4 4 6% 8% 48%	1600
July	1st to 10th	Night	7% 4 2 6% 4 4 5% 5% 7% 10% 46%	3618
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 4 7% 9% 48%	3617
	21st to end	Night	8% 5% 2 6% 4 4 5% 4 6% 8% 48%	4356
August	1st to 10th	Night	11% 6% 2 6% 4 4 4 3 6% 8% 46%	2915
	11th to 20th	Night	7% 7% 2 6% 4 5% 4 3 5% 8% 49%	2875
	21st to end	Night	8% 5% 2 6% 4 5% 5% 3 6% 8% 48%	3271
September	1st to 10th	Night	10% 5% 2 5% 4 5% 4 4 6% 6% 49%	2123
	11th to 20th	Night	8% 5% 1 4 3 3 4 4 5% 7% 56%	2200
	21st to end	Night	15% 7% 2 6% 4 3 4 4 5% 7% 44%	2200
October	1st to 10th	Night	13% 6% 3 6% 3 4 3 3 4 7% 47%	2255
	11th to 20th	Night	18% 8% 3 7% 5% 5% 5% 3 5% 5% 37%	2377
	21st to end	Night	20% 9% 3 8% 4 4 4 4 5% 6% 34%	2652
November	1st to 10th	Night	13% 7% 3 6% 4 5% 4 4 5% 6% 43%	2536
	11th to 20th	Night	16% 11% 4 7% 5% 4 5% 4 6% 7% 31%	2600
	21st to end	Night	19% 14% 5% 8% 4 4 4 3 5% 5% 29%	2685
December	1st to 10th	Night	12% 14% 6% 13% 6% 5% 5% 4 5% 6% 23%	4580
	11th to 20th	Night	17% 19% 7% 12% 6% 5% 4 3 5% 5% 19%	5404
	21st to end	Night	28% 20% 6% 10% 5% 3 4 3 4 4 14%	7014

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	62% 5% 11% 13% 7% 1	3618
	11th to 20th	Day	75% 5% 8% 6% 5% 1	3620
	21st to end	Day	73% 4 10% 8% 5%	4439
February	1st to 10th	Day	64% 6% 9% 14% 7%	1800
	11th to 20th	Day	63% 5% 8% 16% 7% 1	1902
	21st to end	Day	59% 5% 11% 17% 7% 1	1650
March	1st to 10th	Day	57% 4 13% 17% 8% 1	4606
	11th to 20th	Day	48% 5% 16% 22% 8% 1	4980
	21st to end	Day	58% 5% 10% 16% 11% 1	5465
April	1st to 10th	Day	52% 6% 11% 18% 12% 1	2320
	11th to 20th	Day	49% 5% 11% 20% 13% 2	2537
	21st to end	Day	49% 5% 12% 19% 14% 1	2600
May	1st to 10th	Day	51% 6% 9% 19% 13% 3	5897
	11th to 20th	Day	47% 8% 11% 21% 12% 2	5865
	21st to end	Day	41% 6% 9% 21% 18% 5%	6447
June	1st to 10th	Day	40% 7% 11% 25% 14% 3	2776
	11th to 20th	Day	39% 7% 12% 22% 16% 3	2964
	21st to end	Day	39% 8% 13% 21% 17% 2	2800
July	1st to 10th	Day	37% 6% 13% 25% 17% 2	6291
	11th to 20th	Day	33% 6% 14% 27% 19% 1	6285
	21st to end	Day	34% 7% 14% 23% 21% 2	6312
August	1st to 10th	Day	36% 7% 13% 27% 15% 1	4221
	11th to 20th	Day	40% 8% 10% 29% 11% 1	4213
	21st to end	Day	38% 8% 13% 28% 13% 1	4622
September	1st to 10th	Day	39% 8% 13% 24% 14% 2	2256
	11th to 20th	Day	31% 7% 13% 33% 16% 1	2200
	21st to end	Day	43% 7% 12% 24% 14%	2200
October	1st to 10th	Day	30% 5% 11% 31% 21% 1	3496
	11th to 20th	Day	39% 4 11% 27% 18%	3220
	21st to end	Day	44% 5% 13% 24% 13% 1	3180
November	1st to 10th	Day	44% 7% 11% 24% 13% 1	1762
	11th to 20th	Day	53% 5% 13% 19% 9% 1	1800
	21st to end	Day	58% 6% 11% 18% 7% 1	1709
December	1st to 10th	Day	64% 6% 15% 11% 4	2600
	11th to 20th	Day	67% 5% 11% 13% 5%	2789
	21st to end	Day	77% 4 7% 8% 4	3959
January	1st to 10th	Night	59% 5% 10% 18% 6% 1	6348
	11th to 20th	Night	69% 5% 10% 10% 5%	6360
	21st to end	Night	65% 5% 11% 11% 8%	6514
February	1st to 10th	Night	62% 6% 11% 13% 7% 1	2600
	11th to 20th	Night	58% 5% 10% 17% 9% 1	2393
	21st to end	Night	55% 6% 12% 18% 8% 1	1980
March	1st to 10th	Night	50% 4 13% 21% 10% 1	5246
	11th to 20th	Night	39% 6% 14% 25% 15% 1	4980
	21st to end	Night	49% 5% 10% 20% 15% 1	5467
April	1st to 10th	Night	49% 6% 10% 21% 13% 2	2096
	11th to 20th	Night	44% 6% 11% 19% 18% 1	1812
	21st to end	Night	45% 5% 10% 19% 17% 3	1800
May	1st to 10th	Night	53% 6% 8% 16% 14% 3	4060
	11th to 20th	Night	46% 7% 8% 26% 10% 3	4033
	21st to end	Night	38% 6% 12% 22% 18% 4	4429
June	1st to 10th	Night	35% 6% 11% 26% 19% 3	1601
	11th to 20th	Night	36% 7% 12% 26% 17% 2	1416
	21st to end	Night	33% 8% 11% 26% 22% 1	1600
July	1st to 10th	Night	30% 7% 13% 30% 15% 5%	3580
	11th to 20th	Night	31% 7% 14% 29% 17% 1	3572
	21st to end	Night	32% 7% 14% 21% 24% 2	4228
August	1st to 10th	Night	35% 7% 12% 28% 18% 1	2904
	11th to 20th	Night	33% 7% 10% 36% 12% 2	2902
	21st to end	Night	33% 7% 11% 33% 15% 1	3271
September	1st to 10th	Night	32% 8% 12% 29% 17% 2	2123
	11th to 20th	Night	27% 6% 10% 33% 21% 2	2200
	21st to end	Night	41% 6% 11% 27% 14% 1	2200
October	1st to 10th	Night	26% 4 9% 33% 28% 1	3684
	11th to 20th	Night	42% 4 11% 24% 19%	3876
	21st to end	Night	40% 4 11% 30% 14% 1	4365
November	1st to 10th	Night	42% 5% 12% 26% 15% 1	2536
	11th to 20th	Night	51% 5% 13% 20% 10% 1	2600
	21st to end	Night	57% 5% 12% 19% 6%	2685
December	1st to 10th	Night	61% 6% 15% 14% 4	4580
	11th to 20th	Night	66% 5% 12% 12% 6% 1	5407
	21st to end	Night	74% 4 9% 7% 6%	7014

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% 21% 34% 14% 6%	300
	11th to 20th	Day	24% 19% 40% 14% 2 1	300
	21st to end	Day	27% 17% 36% 15% 4 1	330
February	1st to 10th	Day	25% 21% 37% 14% 2 1	300
	11th to 20th	Day	27% 19% 37% 15% 2	300
	21st to end	Day	26% 30% 33% 9% 3	249
March	1st to 10th	Day	28% 22% 31% 15% 4	348
	11th to 20th	Day	25% 14% 35% 19% 6% 1	500
	21st to end	Day	27% 17% 33% 17% 5% 1	550
April	1st to 10th	Day	24% 18% 33% 19% 6% 1	500
	11th to 20th	Day	27% 19% 29% 14% 8% 3	492
	21st to end	Day	26% 17% 30% 16% 8% 3	500
May	1st to 10th	Day	24% 17% 29% 19% 7% 3	503
	11th to 20th	Day	20% 11% 32% 21% 12% 5%	527
	21st to end	Day	15% 11% 25% 26% 16% 6%	573
June	1st to 10th	Day	13% 11% 34% 28% 12% 2	700
	11th to 20th	Day	15% 9% 32% 29% 12% 2	730
	21st to end	Day	12% 11% 33% 27% 14% 4	730
July	1st to 10th	Day	10% 6% 28% 28% 21% 8%	721
	11th to 20th	Day	10% 9% 30% 28% 16% 7%	718
	21st to end	Day	9% 5% 29% 28% 21% 9%	610
August	1st to 10th	Day	8% 4 26% 30% 20% 12%	526
	11th to 20th	Day	13% 5% 24% 29% 18% 11%	519
	21st to end	Day	10% 6% 22% 30% 22% 9%	583
September	1st to 10th	Day	11% 8% 25% 24% 21% 11%	530
	11th to 20th	Day	8% 4 20% 27% 28% 12%	530
	21st to end	Day	17% 11% 25% 22% 17% 8%	530
October	1st to 10th	Day	15% 11% 27% 23% 18% 7%	530
	11th to 20th	Day	19% 18% 31% 24% 7% 2	522
	21st to end	Day	29% 16% 35% 15% 5% 1	392
November	1st to 10th	Day	15% 23% 35% 17% 9% 1	300
	11th to 20th	Day	26% 23% 30% 16% 5% 1	300
	21st to end	Day	28% 20% 34% 13% 5%	254
December	1st to 10th	Day	24% 22% 34% 15% 6% 1	200
	11th to 20th	Day	30% 24% 35% 9% 3 1	200
	21st to end	Day	31% 22% 31% 14% 2	325
January	1st to 10th	Night	23% 18% 34% 20% 5% 1	1000
	11th to 20th	Night	27% 14% 32% 21% 5% 1	1000
	21st to end	Night	22% 15% 33% 24% 5%	891
February	1st to 10th	Night	26% 14% 35% 23% 3	800
	11th to 20th	Night	25% 15% 32% 25% 4	783
	21st to end	Night	26% 16% 37% 19% 2	660
March	1st to 10th	Night	21% 13% 33% 26% 6%	800
	11th to 20th	Night	20% 16% 35% 24% 4 1	800
	21st to end	Night	24% 13% 29% 26% 7% 1	880
April	1st to 10th	Night	22% 15% 33% 26% 4	696
	11th to 20th	Night	22% 12% 33% 24% 7% 1	593
	21st to end	Night	20% 12% 30% 31% 7%	600
May	1st to 10th	Night	21% 10% 29% 30% 8% 1	600
	11th to 20th	Night	22% 7% 27% 33% 12% 1	591
	21st to end	Night	11% 5% 27% 38% 18% 2	650
June	1st to 10th	Night	13% 5% 28% 40% 13%	575
	11th to 20th	Night	10% 6% 28% 44% 12%	416
	21st to end	Night	11% 5% 26% 38% 19% 1	600
July	1st to 10th	Night	9% 2 22% 40% 24% 4	585
	11th to 20th	Night	10% 4 23% 39% 21% 4	582
	21st to end	Night	6% 3 20% 47% 22% 2	657
August	1st to 10th	Night	8% 4 19% 40% 26% 3	597
	11th to 20th	Night	10% 2 20% 36% 30% 3	594
	21st to end	Night	10% 3 18% 37% 29% 2	660
September	1st to 10th	Night	14% 6% 18% 33% 25% 4	723
	11th to 20th	Night	10% 4 18% 34% 32% 3	800
	21st to end	Night	17% 7% 23% 29% 21% 4	800
October	1st to 10th	Night	16% 9% 25% 30% 18% 3	800
	11th to 20th	Night	22% 14% 28% 25% 10% 1	793
	21st to end	Night	25% 13% 30% 26% 6%	836
November	1st to 10th	Night	18% 13% 30% 26% 11% 1	780
	11th to 20th	Night	23% 16% 31% 22% 7% 1	800
	21st to end	Night	27% 13% 34% 19% 6%	800
December	1st to 10th	Night	26% 16% 34% 18% 6%	800
	11th to 20th	Night	26% 15% 35% 20% 4	890
	21st to end	Night	33% 12% 32% 20% 3	1100

Page generated at 2025-10-16 01:50:27. Version ac07

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