Mount Albert Lion's Club
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mount Albert Lion's Club clear sky chart from 2005-11-06 to 2025-08-05.

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% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	126342
	Night	14% 11% 4 10% 6% 5% 5% 4 5% 6% 31%	121678
Transparency	Day	51% 6% 12% 20% 11% 1	129933
	Night	51% 6% 12% 19% 10% 1	126173
Seeing	Day	20% 16% 31% 20% 9% 3	15569
	Night	19% 15% 32% 24% 9% 1	24670

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	12% 13% 5% 14% 6% 6% 5% 3 5% 6% 23%	3597
	11th to 20th	Day	9% 15% 8% 19% 10% 9% 5% 3 4 5% 13%	3843
	21st to end	Day	14% 18% 7% 15% 7% 5% 5% 4 4 5% 15%	4466
February	1st to 10th	Day	14% 16% 5% 13% 8% 8% 5% 4 4 4 19%	1800
	11th to 20th	Day	11% 16% 7% 12% 8% 5% 5% 3 5% 6% 22%	1753
	21st to end	Day	15% 16% 5% 10% 6% 6% 5% 4 4 6% 23%	1530
March	1st to 10th	Day	17% 12% 6% 10% 6% 4 4 3 4 6% 29%	4932
	11th to 20th	Day	10% 14% 6% 10% 6% 5% 6% 4 5% 7% 28%	4980
	21st to end	Day	18% 14% 4 10% 5% 3 3 3 4 4 32%	5465
April	1st to 10th	Day	18% 14% 4 9% 4 5% 4 3 5% 5% 28%	2370
	11th to 20th	Day	19% 12% 2 7% 4 4 3 3 6% 5% 35%	2450
	21st to end	Day	19% 11% 4 8% 4 4 3 3 5% 6% 33%	2600
May	1st to 10th	Day	17% 11% 3 8% 5% 4 4 3 5% 7% 33%	5922
	11th to 20th	Day	14% 11% 3 8% 5% 5% 4 3 5% 7% 34%	6318
	21st to end	Day	18% 8% 2 7% 4 4 4 3 5% 7% 37%	6949
June	1st to 10th	Day	16% 8% 3 6% 4 4 5% 4 7% 8% 35%	2800
	11th to 20th	Day	13% 6% 2 6% 5% 5% 6% 4 6% 9% 38%	2800
	21st to end	Day	14% 7% 3 6% 5% 4 5% 4 6% 9% 37%	2988
July	1st to 10th	Day	12% 6% 3 7% 5% 5% 5% 5% 6% 9% 37%	6497
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 4 6% 9% 44%	6360
	21st to end	Day	8% 5% 2 5% 5% 4 5% 4 7% 8% 46%	6563
August	1st to 10th	Day	14% 8% 3 6% 4 4 5% 4 6% 8% 36%	4156
	11th to 20th	Day	13% 7% 3 8% 5% 4 5% 4 7% 10% 34%	4044
	21st to end	Day	10% 6% 2 6% 4 4 5% 4 6% 8% 44%	4352
September	1st to 10th	Day	14% 7% 2 6% 5% 5% 4 4 5% 8% 41%	2280
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 5% 8% 43%	2180
	21st to end	Day	13% 7% 3 9% 5% 4 4 4 5% 7% 37%	2043
October	1st to 10th	Day	18% 9% 3 8% 5% 5% 4 3 5% 6% 35%	1900
	11th to 20th	Day	20% 11% 4 8% 5% 5% 5% 3 5% 7% 27%	1900
	21st to end	Day	25% 14% 4 9% 5% 3 4 3 5% 5% 22%	2090
November	1st to 10th	Day	14% 14% 3 8% 6% 5% 5% 3 6% 6% 30%	1668
	11th to 20th	Day	13% 17% 4 10% 7% 5% 5% 5% 5% 5% 24%	1600
	21st to end	Day	17% 18% 6% 12% 5% 5% 5% 4 4 5% 18%	1600
December	1st to 10th	Day	15% 22% 8% 15% 8% 6% 5% 3 5% 4 9%	2600
	11th to 20th	Day	16% 18% 6% 12% 7% 5% 4 3 4 5% 20%	2986
	21st to end	Day	22% 15% 7% 16% 6% 6% 5% 3 4 5% 12%	3960
January	1st to 10th	Night	13% 14% 6% 16% 8% 7% 5% 4 5% 5% 17%	6349
	11th to 20th	Night	10% 13% 7% 19% 10% 6% 6% 4 5% 5% 14%	6025
	21st to end	Night	13% 14% 6% 14% 7% 6% 5% 4 6% 6% 19%	6490
February	1st to 10th	Night	12% 16% 5% 12% 8% 6% 6% 4 5% 5% 21%	2600
	11th to 20th	Night	13% 15% 6% 11% 7% 7% 5% 4 5% 5% 23%	2533
	21st to end	Night	12% 13% 5% 12% 6% 6% 4 4 6% 6% 26%	2096
March	1st to 10th	Night	14% 11% 4 11% 6% 5% 5% 4 5% 6% 29%	4908
	11th to 20th	Night	9% 10% 4 9% 5% 5% 5% 5% 7% 8% 33%	4979
	21st to end	Night	17% 9% 4 12% 5% 4 4 3 4 5% 32%	5467
April	1st to 10th	Night	18% 12% 4 8% 5% 4 4 4 5% 6% 29%	2029
	11th to 20th	Night	16% 9% 3 7% 5% 4 4 4 4 6% 37%	1917
	21st to end	Night	16% 11% 4 7% 4 4 4 4 5% 8% 34%	1800
May	1st to 10th	Night	19% 9% 3 7% 5% 4 4 4 6% 5% 35%	4017
	11th to 20th	Night	12% 7% 2 6% 4 5% 5% 4 7% 7% 40%	3575
	21st to end	Night	19% 6% 2 5% 4 4 4 3 4 7% 42%	3926
June	1st to 10th	Night	13% 6% 3 7% 5% 4 5% 4 6% 7% 40%	1600
	11th to 20th	Night	10% 5% 2 6% 5% 4 5% 5% 7% 8% 42%	1599
	21st to end	Night	12% 7% 2 7% 5% 4 4 4 6% 7% 42%	1400
July	1st to 10th	Night	8% 6% 2 6% 5% 4 5% 4 6% 8% 45%	3458
	11th to 20th	Night	11% 5% 2 5% 3 3 4 4 5% 8% 49%	3600
	21st to end	Night	9% 5% 1 5% 4 3 4 4 6% 8% 51%	4285
August	1st to 10th	Night	9% 6% 3 6% 4 4 4 4 6% 7% 48%	2861
	11th to 20th	Night	13% 6% 2 5% 4 3 3 3 6% 8% 48%	2785
	21st to end	Night	10% 6% 2 6% 4 4 5% 3 5% 8% 47%	3270
September	1st to 10th	Night	10% 6% 2 7% 4 5% 4 3 6% 7% 46%	1900
	11th to 20th	Night	11% 5% 2 5% 4 4 3 3 4 7% 51%	1997
	21st to end	Night	15% 7% 3 6% 4 4 5% 2 5% 7% 41%	2136
October	1st to 10th	Night	16% 6% 4 8% 5% 4 4 4 6% 6% 39%	2280
	11th to 20th	Night	17% 10% 3 8% 6% 5% 5% 4 5% 6% 31%	2280
	21st to end	Night	22% 11% 3 8% 5% 5% 5% 4 6% 6% 26%	2508
November	1st to 10th	Night	17% 12% 3 7% 4 4 4 3 6% 6% 33%	2624
	11th to 20th	Night	16% 15% 5% 9% 5% 6% 5% 3 6% 6% 25%	2800
	21st to end	Night	17% 16% 5% 10% 6% 4 5% 4 6% 6% 21%	2800
December	1st to 10th	Night	15% 17% 7% 14% 8% 7% 5% 4 5% 5% 12%	4580
	11th to 20th	Night	13% 18% 6% 14% 7% 6% 5% 4 5% 5% 18%	5208
	21st to end	Night	21% 17% 6% 16% 7% 5% 5% 4 4 5% 12%	6996

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	60% 6% 12% 13% 8%	3598
	11th to 20th	Day	73% 5% 10% 8% 4	3876
	21st to end	Day	70% 6% 9% 8% 6% 1	4466
February	1st to 10th	Day	67% 6% 9% 14% 4 1	1800
	11th to 20th	Day	62% 7% 8% 15% 6% 1	1762
	21st to end	Day	63% 5% 9% 16% 7% 1	1530
March	1st to 10th	Day	56% 5% 13% 13% 12%	4935
	11th to 20th	Day	53% 6% 14% 18% 7% 2	4980
	21st to end	Day	54% 5% 7% 18% 14% 1	5465
April	1st to 10th	Day	57% 6% 8% 18% 10% 1	2370
	11th to 20th	Day	49% 6% 9% 20% 14% 1	2450
	21st to end	Day	52% 6% 10% 18% 12% 3	2600
May	1st to 10th	Day	49% 6% 12% 18% 11% 5%	5931
	11th to 20th	Day	49% 8% 10% 16% 18% 1	6322
	21st to end	Day	46% 5% 12% 20% 14% 3	6949
June	1st to 10th	Day	45% 7% 13% 20% 15% 1	2800
	11th to 20th	Day	40% 7% 14% 23% 15% 1	2800
	21st to end	Day	43% 7% 13% 24% 12% 1	2988
July	1st to 10th	Day	42% 5% 14% 23% 14% 1	6428
	11th to 20th	Day	35% 6% 13% 31% 15% 1	6285
	21st to end	Day	34% 6% 13% 32% 14%	6375
August	1st to 10th	Day	44% 7% 14% 23% 12% 1	4143
	11th to 20th	Day	43% 7% 15% 26% 9%	4083
	21st to end	Day	36% 6% 13% 34% 11% 1	4352
September	1st to 10th	Day	40% 7% 14% 28% 10% 1	2280
	11th to 20th	Day	37% 7% 14% 28% 14%	2180
	21st to end	Day	46% 7% 13% 25% 9%	2043
October	1st to 10th	Day	43% 5% 13% 26% 12% 1	3160
	11th to 20th	Day	47% 4 14% 20% 14%	3140
	21st to end	Day	57% 5% 14% 18% 5%	3428
November	1st to 10th	Day	52% 7% 14% 18% 8% 1	1668
	11th to 20th	Day	59% 7% 12% 13% 8% 1	1600
	21st to end	Day	67% 6% 11% 14% 2	1600
December	1st to 10th	Day	77% 5% 10% 7% 2	2600
	11th to 20th	Day	67% 6% 10% 10% 7%	2986
	21st to end	Day	75% 5% 7% 8% 5%	3960
January	1st to 10th	Night	64% 8% 12% 12% 4	6349
	11th to 20th	Night	69% 7% 11% 9% 4	6066
	21st to end	Night	62% 6% 12% 11% 8% 1	6490
February	1st to 10th	Night	63% 6% 10% 16% 5% 1	2600
	11th to 20th	Night	59% 7% 10% 17% 7%	2535
	21st to end	Night	55% 6% 13% 17% 8%	2096
March	1st to 10th	Night	55% 6% 10% 17% 11% 2	4918
	11th to 20th	Night	44% 7% 17% 21% 8% 2	4980
	21st to end	Night	50% 7% 9% 17% 14% 2	5467
April	1st to 10th	Night	55% 4 9% 19% 11% 1	2029
	11th to 20th	Night	48% 5% 9% 21% 15% 2	1917
	21st to end	Night	49% 5% 11% 18% 16% 2	1800
May	1st to 10th	Night	49% 5% 11% 15% 14% 6%	4024
	11th to 20th	Night	41% 7% 13% 22% 15% 2	3576
	21st to end	Night	42% 6% 13% 24% 13% 2	3927
June	1st to 10th	Night	41% 6% 11% 24% 16% 2	1600
	11th to 20th	Night	38% 6% 13% 22% 20% 2	1599
	21st to end	Night	39% 7% 14% 24% 15% 1	1400
July	1st to 10th	Night	37% 4 15% 26% 17% 1	3418
	11th to 20th	Night	33% 5% 13% 31% 17% 1	3552
	21st to end	Night	31% 6% 12% 32% 18% 1	4158
August	1st to 10th	Night	36% 5% 13% 30% 15% 2	2850
	11th to 20th	Night	34% 5% 18% 30% 12% 1	2812
	21st to end	Night	35% 6% 13% 33% 12% 1	3270
September	1st to 10th	Night	36% 6% 16% 27% 14% 1	1900
	11th to 20th	Night	31% 6% 12% 32% 18% 1	1997
	21st to end	Night	42% 6% 12% 27% 12%	2136
October	1st to 10th	Night	35% 5% 10% 28% 22% 1	3800
	11th to 20th	Night	47% 5% 15% 21% 12%	3779
	21st to end	Night	45% 7% 15% 25% 7%	4120
November	1st to 10th	Night	49% 6% 12% 22% 10% 1	2624
	11th to 20th	Night	57% 7% 12% 15% 8% 1	2800
	21st to end	Night	61% 8% 15% 13% 3	2800
December	1st to 10th	Night	71% 5% 12% 9% 2	4580
	11th to 20th	Night	67% 6% 8% 12% 7%	5208
	21st to end	Night	73% 6% 10% 8% 3	6996

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% 29% 32% 17% 5% 1	200
	11th to 20th	Day	23% 26% 31% 15% 4 1	260
	21st to end	Day	23% 25% 36% 14% 2	330
February	1st to 10th	Day	25% 30% 32% 10% 3	300
	11th to 20th	Day	27% 25% 40% 7% 1	300
	21st to end	Day	33% 22% 36% 9%	269
March	1st to 10th	Day	25% 22% 36% 15% 4	500
	11th to 20th	Day	23% 25% 31% 18% 3 1	500
	21st to end	Day	31% 19% 29% 17% 4 1	550
April	1st to 10th	Day	28% 22% 32% 12% 6%	500
	11th to 20th	Day	32% 19% 24% 16% 6% 3	492
	21st to end	Day	25% 17% 34% 15% 8% 1	500
May	1st to 10th	Day	20% 17% 32% 19% 9% 4	503
	11th to 20th	Day	20% 13% 29% 24% 10% 3	527
	21st to end	Day	17% 13% 31% 23% 12% 4	573
June	1st to 10th	Day	17% 16% 31% 26% 8% 1	530
	11th to 20th	Day	15% 15% 30% 26% 12% 2	530
	21st to end	Day	18% 11% 35% 25% 9% 2	718
July	1st to 10th	Day	11% 8% 31% 30% 16% 4	585
	11th to 20th	Day	12% 9% 27% 29% 15% 7%	524
	21st to end	Day	9% 7% 35% 31% 13% 5%	576
August	1st to 10th	Day	13% 9% 26% 28% 16% 8%	502
	11th to 20th	Day	12% 9% 23% 27% 22% 8%	479
	21st to end	Day	14% 9% 30% 26% 15% 7%	539
September	1st to 10th	Day	13% 9% 28% 25% 16% 7%	490
	11th to 20th	Day	9% 9% 25% 23% 20% 13%	490
	21st to end	Day	14% 14% 31% 22% 13% 6%	490
October	1st to 10th	Day	23% 12% 29% 19% 13% 4	490
	11th to 20th	Day	23% 21% 32% 17% 7% 1	490
	21st to end	Day	30% 19% 32% 16% 4	539
November	1st to 10th	Day	25% 22% 30% 16% 6% 1	273
	11th to 20th	Day	24% 28% 30% 15% 4 2	200
	21st to end	Day	27% 23% 39% 11% 1	200
December	1st to 10th	Day	25% 23% 37% 12% 5%	200
	11th to 20th	Day	30% 24% 32% 11% 3 1	200
	21st to end	Day	25% 23% 37% 11% 2 1	220
January	1st to 10th	Night	22% 23% 37% 13% 4 1	800
	11th to 20th	Night	25% 18% 34% 19% 4 1	800
	21st to end	Night	20% 16% 37% 21% 6%	880
February	1st to 10th	Night	21% 21% 38% 19% 1	800
	11th to 20th	Night	23% 19% 37% 18% 2	783
	21st to end	Night	20% 23% 37% 16% 3	660
March	1st to 10th	Night	20% 22% 37% 18% 3	800
	11th to 20th	Night	21% 22% 35% 17% 4 1	800
	21st to end	Night	20% 18% 34% 22% 6%	880
April	1st to 10th	Night	26% 16% 34% 21% 3	800
	11th to 20th	Night	20% 16% 36% 19% 8% 1	733
	21st to end	Night	22% 13% 33% 25% 8%	600
May	1st to 10th	Night	19% 11% 29% 29% 11% 1	590
	11th to 20th	Night	16% 8% 35% 30% 10% 1	394
	21st to end	Night	14% 8% 28% 34% 15% 1	433
June	1st to 10th	Night	14% 8% 35% 34% 10%	400
	11th to 20th	Night	12% 8% 33% 34% 13% 1	400
	21st to end	Night	16% 6% 30% 35% 12% 1	400
July	1st to 10th	Night	7% 7% 27% 41% 18% 1	390
	11th to 20th	Night	11% 6% 28% 36% 19% 1	388
	21st to end	Night	8% 5% 28% 39% 19% 1	592
August	1st to 10th	Night	11% 2 22% 36% 27% 1	579
	11th to 20th	Night	8% 5% 19% 39% 26% 3	564
	21st to end	Night	11% 6% 28% 33% 19% 2	708
September	1st to 10th	Night	12% 8% 27% 31% 18% 4	760
	11th to 20th	Night	13% 7% 24% 29% 22% 5%	760
	21st to end	Night	18% 10% 22% 31% 15% 4	760
October	1st to 10th	Night	19% 9% 31% 24% 15% 1	760
	11th to 20th	Night	21% 17% 32% 21% 9% 1	760
	21st to end	Night	27% 14% 34% 20% 4	836
November	1st to 10th	Night	23% 17% 31% 20% 7% 1	780
	11th to 20th	Night	22% 22% 31% 19% 6% 1	800
	21st to end	Night	25% 20% 30% 21% 4	800
December	1st to 10th	Night	26% 19% 36% 15% 3	800
	11th to 20th	Night	21% 23% 36% 16% 3 1	800
	21st to end	Night	28% 19% 35% 15% 2	880

Page generated at 2025-08-02 01:32:25. Version ac07

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