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 2024-03-23.

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	15% 10% 4 8% 6% 4 5% 5% 5% 7% 31%	78877
	Night	15% 11% 5% 8% 7% 4 5% 5% 5% 6% 30%	80976
Transparency	Day	52% 7% 12% 19% 10% 1	78590
	Night	52% 7% 12% 18% 9% 1	80797
Seeing	Day	19% 16% 31% 21% 10% 3	13732
	Night	19% 14% 32% 24% 9% 1	23061

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% 16% 5% 10% 6% 4 5% 4 4 5% 26%	2517
	11th to 20th	Day	11% 16% 8% 15% 10% 6% 5% 4 4 5% 16%	2712
	21st to end	Day	19% 20% 8% 11% 8% 3 4 4 4 4 14%	3124
February	1st to 10th	Day	15% 15% 5% 12% 9% 5% 7% 5% 5% 4 19%	1710
	11th to 20th	Day	11% 13% 9% 11% 8% 4 5% 4 5% 6% 23%	1663
	21st to end	Day	16% 15% 6% 9% 7% 5% 5% 4 4 6% 23%	1456
March	1st to 10th	Day	14% 12% 5% 8% 8% 4 5% 4 5% 5% 29%	2087
	11th to 20th	Day	11% 14% 6% 8% 7% 3 5% 5% 4 5% 31%	2090
	21st to end	Day	18% 11% 4 7% 6% 3 4 4 4 5% 35%	2200
April	1st to 10th	Day	19% 12% 5% 8% 5% 3 5% 4 5% 6% 28%	2132
	11th to 20th	Day	18% 11% 3 6% 5% 3 3 4 6% 5% 36%	2202
	21st to end	Day	20% 10% 4 7% 5% 3 4 4 5% 6% 33%	2340
May	1st to 10th	Day	17% 10% 3 6% 6% 3 5% 5% 5% 7% 34%	2346
	11th to 20th	Day	15% 8% 3 5% 5% 3 4 5% 5% 6% 40%	2478
	21st to end	Day	13% 5% 2 5% 6% 3 5% 6% 5% 7% 42%	2725
June	1st to 10th	Day	17% 7% 3 5% 5% 3 5% 5% 6% 9% 36%	2520
	11th to 20th	Day	14% 6% 2 5% 5% 3 6% 5% 6% 9% 39%	2520
	21st to end	Day	14% 7% 3 5% 5% 3 5% 6% 5% 9% 38%	2688
July	1st to 10th	Day	9% 4 2 5% 5% 3 6% 5% 6% 9% 45%	2574
	11th to 20th	Day	10% 6% 3 6% 6% 4 6% 6% 7% 9% 37%	2520
	21st to end	Day	10% 6% 2 6% 7% 4 7% 6% 7% 9% 36%	2602
August	1st to 10th	Day	11% 6% 3 6% 6% 3 5% 6% 7% 10% 37%	2327
	11th to 20th	Day	9% 6% 2 7% 6% 4 6% 6% 7% 9% 37%	2303
	21st to end	Day	12% 7% 3 6% 6% 3 5% 5% 7% 8% 38%	2478
September	1st to 10th	Day	14% 6% 2 5% 6% 3 5% 5% 5% 9% 40%	2160
	11th to 20th	Day	13% 6% 3 5% 6% 3 5% 5% 5% 8% 42%	2066
	21st to end	Day	13% 7% 3 8% 6% 3 5% 5% 5% 7% 38%	1936
October	1st to 10th	Day	19% 10% 3 6% 6% 4 4 4 5% 6% 34%	1800
	11th to 20th	Day	21% 11% 4 7% 7% 4 4 5% 4 7% 26%	1800
	21st to end	Day	26% 14% 4 8% 6% 3 3 5% 5% 4 21%	1980
November	1st to 10th	Day	15% 13% 4 7% 7% 3 5% 4 6% 6% 30%	1583
	11th to 20th	Day	14% 16% 5% 9% 8% 4 5% 7% 5% 5% 23%	1520
	21st to end	Day	18% 17% 6% 10% 7% 4 5% 4 4 6% 19%	1520
December	1st to 10th	Day	16% 17% 8% 15% 9% 4 6% 4 4 6% 12%	1520
	11th to 20th	Day	18% 14% 5% 9% 8% 5% 6% 4 5% 7% 19%	1906
	21st to end	Day	25% 16% 7% 13% 7% 4 5% 4 4 3 12%	2772
January	1st to 10th	Night	15% 16% 6% 11% 9% 5% 5% 5% 5% 5% 17%	4429
	11th to 20th	Night	12% 13% 7% 15% 11% 5% 6% 5% 5% 5% 17%	4244
	21st to end	Night	18% 14% 7% 10% 8% 4 5% 5% 5% 5% 17%	4532
February	1st to 10th	Night	13% 15% 7% 10% 9% 5% 6% 6% 4 5% 21%	2470
	11th to 20th	Night	13% 14% 6% 10% 7% 5% 6% 5% 5% 6% 24%	2403
	21st to end	Night	13% 12% 5% 10% 7% 4 5% 4 6% 6% 27%	1995
March	1st to 10th	Night	13% 12% 4 8% 7% 4 5% 4 5% 6% 32%	2080
	11th to 20th	Night	14% 13% 6% 8% 7% 3 4 4 5% 5% 33%	2089
	21st to end	Night	15% 9% 4 7% 6% 3 5% 4 5% 5% 37%	2201
April	1st to 10th	Night	19% 11% 5% 7% 6% 3 5% 4 5% 6% 30%	1827
	11th to 20th	Night	16% 8% 3 7% 5% 3 4 5% 4 6% 37%	1723
	21st to end	Night	17% 11% 4 6% 5% 3 4 4 4 8% 34%	1620
May	1st to 10th	Night	17% 6% 2 6% 5% 3 4 5% 7% 7% 38%	1612
	11th to 20th	Night	13% 6% 2 5% 4 3 4 5% 6% 7% 45%	1415
	21st to end	Night	11% 4 2 4 4 2 5% 5% 5% 7% 51%	1550
June	1st to 10th	Night	13% 5% 4 5% 6% 4 5% 5% 6% 7% 41%	1440
	11th to 20th	Night	11% 5% 2 6% 5% 3 4 6% 7% 8% 43%	1440
	21st to end	Night	12% 6% 3 6% 5% 3 4 5% 6% 7% 43%	1260
July	1st to 10th	Night	7% 3 2 5% 5% 2 5% 5% 4 7% 54%	1376
	11th to 20th	Night	9% 6% 2 4 4 3 4 5% 5% 9% 48%	1440
	21st to end	Night	7% 4 2 5% 5% 3 5% 6% 6% 9% 48%	1712
August	1st to 10th	Night	8% 5% 3 5% 4 3 4 6% 6% 8% 50%	1611
	11th to 20th	Night	7% 3 2 4 4 3 4 5% 8% 10% 49%	1598
	21st to end	Night	9% 6% 3 6% 6% 4 4 4 5% 7% 46%	1858
September	1st to 10th	Night	10% 6% 2 6% 6% 3 5% 4 6% 7% 46%	1800
	11th to 20th	Night	12% 5% 3 4 5% 3 4 3 4 7% 50%	1891
	21st to end	Night	14% 7% 3 5% 5% 3 5% 3 5% 7% 42%	2023
October	1st to 10th	Night	16% 6% 4 8% 6% 3 4 5% 6% 6% 37%	2160
	11th to 20th	Night	19% 10% 3 7% 7% 4 5% 5% 6% 6% 30%	2160
	21st to end	Night	23% 11% 3 7% 6% 4 5% 5% 5% 6% 25%	2376
November	1st to 10th	Night	17% 11% 4 6% 4 3 4 4 6% 7% 33%	2489
	11th to 20th	Night	17% 13% 5% 8% 6% 4 5% 4 6% 7% 25%	2660
	21st to end	Night	17% 14% 6% 9% 7% 4 5% 5% 5% 6% 22%	2660
December	1st to 10th	Night	18% 15% 7% 11% 8% 4 5% 5% 5% 6% 16%	2660
	11th to 20th	Night	14% 17% 6% 12% 8% 4 5% 5% 5% 5% 18%	3288
	21st to end	Night	25% 16% 6% 14% 7% 4 5% 4 4 5% 11%	4884

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% 5% 16% 12% 7%	2518
	11th to 20th	Day	70% 5% 11% 9% 4	2712
	21st to end	Day	72% 6% 9% 8% 4 1	3124
February	1st to 10th	Day	67% 6% 9% 14% 4 1	1710
	11th to 20th	Day	61% 7% 8% 16% 7% 1	1672
	21st to end	Day	62% 5% 9% 16% 7% 1	1456
March	1st to 10th	Day	56% 6% 13% 16% 10%	2090
	11th to 20th	Day	55% 5% 10% 17% 11% 2	2090
	21st to end	Day	53% 5% 8% 17% 15% 2	2200
April	1st to 10th	Day	57% 6% 9% 17% 10% 1	2132
	11th to 20th	Day	48% 6% 10% 21% 14% 1	2202
	21st to end	Day	51% 6% 10% 18% 12% 3	2340
May	1st to 10th	Day	50% 5% 10% 19% 14% 2	2346
	11th to 20th	Day	43% 7% 10% 23% 15% 1	2482
	21st to end	Day	40% 7% 15% 23% 13% 2	2725
June	1st to 10th	Day	44% 7% 13% 20% 15% 1	2520
	11th to 20th	Day	40% 7% 13% 23% 16% 1	2520
	21st to end	Day	42% 7% 13% 24% 13% 1	2688
July	1st to 10th	Day	34% 7% 14% 25% 18% 2	2504
	11th to 20th	Day	39% 9% 14% 27% 10% 1	2445
	21st to end	Day	42% 9% 14% 22% 12% 1	2456
August	1st to 10th	Day	39% 9% 16% 23% 11% 2	2314
	11th to 20th	Day	39% 9% 16% 25% 11%	2303
	21st to end	Day	41% 7% 14% 26% 11% 1	2478
September	1st to 10th	Day	41% 8% 14% 27% 10% 1	2160
	11th to 20th	Day	38% 7% 14% 28% 13%	2066
	21st to end	Day	46% 7% 14% 26% 8%	1936
October	1st to 10th	Day	51% 5% 13% 19% 11% 1	1800
	11th to 20th	Day	57% 6% 13% 17% 6% 1	1800
	21st to end	Day	64% 6% 12% 13% 5%	1980
November	1st to 10th	Day	52% 8% 14% 18% 8% 1	1583
	11th to 20th	Day	60% 7% 12% 13% 8% 1	1520
	21st to end	Day	66% 6% 11% 14% 2	1520
December	1st to 10th	Day	72% 7% 10% 9% 2	1520
	11th to 20th	Day	64% 9% 12% 11% 5%	1906
	21st to end	Day	77% 4 9% 7% 2	2772
January	1st to 10th	Night	63% 8% 15% 10% 4	4429
	11th to 20th	Night	67% 7% 13% 10% 3 1	4244
	21st to end	Night	66% 6% 13% 10% 4 1	4532
February	1st to 10th	Night	63% 6% 10% 17% 4 1	2470
	11th to 20th	Night	58% 7% 10% 17% 7%	2405
	21st to end	Night	55% 7% 13% 17% 8%	1995
March	1st to 10th	Night	52% 5% 13% 18% 9% 1	2090
	11th to 20th	Night	52% 6% 9% 21% 10% 2	2090
	21st to end	Night	48% 6% 9% 20% 15% 2	2201
April	1st to 10th	Night	53% 5% 9% 20% 12% 1	1827
	11th to 20th	Night	47% 5% 9% 21% 16% 2	1723
	21st to end	Night	49% 6% 11% 18% 15% 2	1620
May	1st to 10th	Night	43% 5% 11% 22% 16% 3	1612
	11th to 20th	Night	39% 5% 10% 24% 18% 3	1416
	21st to end	Night	32% 6% 15% 25% 17% 4	1551
June	1st to 10th	Night	41% 6% 11% 24% 16% 2	1440
	11th to 20th	Night	37% 6% 12% 22% 21% 2	1440
	21st to end	Night	38% 7% 14% 24% 15% 1	1260
July	1st to 10th	Night	28% 6% 12% 29% 22% 2	1336
	11th to 20th	Night	33% 6% 13% 31% 16% 1	1392
	21st to end	Night	30% 8% 15% 30% 14% 2	1617
August	1st to 10th	Night	32% 7% 18% 30% 13% 1	1600
	11th to 20th	Night	28% 8% 17% 31% 15% 1	1598
	21st to end	Night	36% 7% 13% 28% 14% 1	1858
September	1st to 10th	Night	36% 6% 17% 26% 14% 1	1800
	11th to 20th	Night	33% 6% 12% 33% 16% 1	1891
	21st to end	Night	41% 6% 13% 28% 12%	2023
October	1st to 10th	Night	46% 7% 12% 19% 14% 1	2160
	11th to 20th	Night	52% 8% 14% 19% 7%	2160
	21st to end	Night	58% 8% 11% 14% 9%	2376
November	1st to 10th	Night	48% 6% 12% 22% 10% 1	2489
	11th to 20th	Night	56% 7% 13% 15% 8% 2	2660
	21st to end	Night	60% 8% 15% 13% 3	2660
December	1st to 10th	Night	68% 7% 11% 11% 3	2660
	11th to 20th	Night	66% 7% 10% 13% 3	3288
	21st to end	Night	76% 6% 9% 7% 2	4884

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% 26% 32% 18% 6% 1	180
	11th to 20th	Day	21% 28% 30% 15% 4 1	234
	21st to end	Day	23% 23% 37% 15% 2	297
February	1st to 10th	Day	22% 29% 34% 11% 3	270
	11th to 20th	Day	23% 24% 44% 8% 1	270
	21st to end	Day	34% 23% 34% 9%	244
March	1st to 10th	Day	23% 22% 36% 15% 4	460
	11th to 20th	Day	21% 25% 32% 18% 3 1	460
	21st to end	Day	30% 19% 29% 17% 5% 1	470
April	1st to 10th	Day	25% 21% 34% 12% 7%	420
	11th to 20th	Day	29% 19% 24% 17% 7% 3	412
	21st to end	Day	24% 16% 35% 16% 7% 2	420
May	1st to 10th	Day	21% 15% 31% 21% 9% 4	423
	11th to 20th	Day	21% 14% 28% 24% 9% 4	447
	21st to end	Day	15% 12% 31% 24% 14% 4	485
June	1st to 10th	Day	17% 15% 29% 28% 9% 1	450
	11th to 20th	Day	16% 14% 26% 27% 14% 2	450
	21st to end	Day	16% 10% 35% 27% 10% 2	618
July	1st to 10th	Day	9% 8% 30% 30% 18% 5%	499
	11th to 20th	Day	12% 8% 27% 30% 16% 7%	444
	21st to end	Day	8% 7% 35% 32% 13% 5%	488
August	1st to 10th	Day	11% 9% 26% 29% 16% 9%	446
	11th to 20th	Day	11% 8% 23% 29% 22% 8%	439
	21st to end	Day	13% 9% 30% 25% 15% 7%	495
September	1st to 10th	Day	13% 8% 29% 26% 17% 8%	450
	11th to 20th	Day	10% 10% 27% 23% 18% 12%	450
	21st to end	Day	13% 14% 32% 22% 13% 6%	450
October	1st to 10th	Day	24% 11% 28% 19% 14% 4	450
	11th to 20th	Day	24% 20% 32% 16% 6% 1	450
	21st to end	Day	31% 18% 31% 16% 4	495
November	1st to 10th	Day	23% 23% 30% 17% 7% 1	248
	11th to 20th	Day	22% 28% 29% 15% 4 2	180
	21st to end	Day	27% 21% 40% 11% 1	180
December	1st to 10th	Day	23% 23% 37% 13% 4	180
	11th to 20th	Day	27% 24% 33% 12% 3 1	180
	21st to end	Day	27% 22% 38% 11% 2	198
January	1st to 10th	Night	23% 22% 36% 14% 4 1	760
	11th to 20th	Night	25% 18% 33% 19% 4 1	760
	21st to end	Night	19% 15% 37% 22% 6%	836
February	1st to 10th	Night	20% 21% 38% 19% 1	760
	11th to 20th	Night	22% 18% 38% 19% 3	743
	21st to end	Night	21% 23% 37% 16% 3	628
March	1st to 10th	Night	19% 21% 37% 19% 3	760
	11th to 20th	Night	21% 21% 35% 18% 4 1	760
	21st to end	Night	20% 16% 35% 23% 6%	801
April	1st to 10th	Night	24% 17% 34% 22% 3	720
	11th to 20th	Night	20% 16% 35% 20% 8% 1	659
	21st to end	Night	22% 12% 32% 26% 8%	540
May	1st to 10th	Night	20% 8% 29% 30% 11% 2	532
	11th to 20th	Night	16% 6% 36% 30% 10% 1	354
	21st to end	Night	12% 8% 29% 35% 16% 1	389
June	1st to 10th	Night	13% 7% 35% 34% 11%	360
	11th to 20th	Night	13% 7% 33% 34% 14% 1	360
	21st to end	Night	16% 6% 29% 36% 13% 1	360
July	1st to 10th	Night	6% 7% 25% 41% 20% 1	350
	11th to 20th	Night	10% 6% 29% 35% 19% 1	348
	21st to end	Night	7% 6% 28% 39% 19% 1	532
August	1st to 10th	Night	11% 3 22% 36% 27% 1	537
	11th to 20th	Night	6% 5% 19% 41% 26% 3	534
	21st to end	Night	11% 5% 27% 34% 19% 3	670
September	1st to 10th	Night	12% 8% 27% 32% 19% 4	720
	11th to 20th	Night	14% 7% 26% 29% 20% 5%	720
	21st to end	Night	17% 10% 22% 31% 15% 4	720
October	1st to 10th	Night	19% 9% 31% 24% 16% 1	720
	11th to 20th	Night	22% 17% 32% 20% 8% 1	720
	21st to end	Night	28% 14% 34% 20% 4	792
November	1st to 10th	Night	24% 16% 31% 21% 8% 1	740
	11th to 20th	Night	22% 21% 31% 19% 6% 1	760
	21st to end	Night	24% 20% 30% 21% 4	760
December	1st to 10th	Night	27% 19% 36% 14% 3	760
	11th to 20th	Night	21% 22% 36% 16% 3 1	760
	21st to end	Night	29% 19% 35% 15% 2	836

Page generated at 2024-03-19 23:31:04. Version ac07

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