Observatoire "Hawaii mini" du star pit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire "Hawaii mini" du star pit clear sky chart from 2005-11-06 to 2026-03-18.

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	17% 12% 4 9% 5% 5% 4 4 5% 6% 28%	130760
	Night	16% 14% 5% 11% 6% 5% 4 3 4 5% 27%	130810
Transparency	Day	55% 6% 11% 18% 8% 1	134212
	Night	56% 7% 11% 17% 8% 1	135446
Seeing	Day	25% 21% 32% 16% 5% 1	17142
	Night	23% 19% 31% 20% 6% 1	25642

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% 19% 6% 14% 7% 4 4 3 4 5% 22%	4587
	11th to 20th	Day	9% 17% 8% 22% 10% 7% 3 2 3 3 15%	4650
	21st to end	Day	5% 8% 7% 17% 8% 6% 5% 5% 5% 7% 28%	5124
February	1st to 10th	Day	11% 16% 5% 13% 9% 7% 5% 4 4 5% 23%	1731
	11th to 20th	Day	13% 17% 7% 13% 7% 5% 4 2 4 4 24%	1983
	21st to end	Day	11% 15% 6% 13% 7% 5% 4 3 5% 5% 28%	1730
March	1st to 10th	Day	17% 17% 6% 12% 6% 5% 4 3 4 4 23%	4576
	11th to 20th	Day	13% 17% 5% 9% 6% 5% 4 4 5% 6% 25%	4911
	21st to end	Day	18% 16% 6% 10% 5% 3 3 2 3 4 29%	5687
April	1st to 10th	Day	22% 16% 3 9% 5% 4 3 3 3 5% 26%	2400
	11th to 20th	Day	19% 16% 3 7% 4 3 3 3 4 5% 34%	2512
	21st to end	Day	22% 13% 3 7% 4 4 4 3 4 5% 30%	2600
May	1st to 10th	Day	24% 13% 3 7% 6% 4 4 3 4 6% 25%	5886
	11th to 20th	Day	22% 10% 3 8% 5% 5% 5% 4 5% 6% 26%	6318
	21st to end	Day	19% 10% 3 8% 5% 5% 5% 4 5% 6% 28%	7260
June	1st to 10th	Day	22% 9% 3 7% 5% 5% 5% 5% 6% 8% 26%	3000
	11th to 20th	Day	22% 8% 2 6% 5% 4 5% 4 6% 7% 33%	3000
	21st to end	Day	24% 10% 3 9% 6% 5% 4 3 5% 6% 25%	3000
July	1st to 10th	Day	19% 10% 3 8% 6% 5% 5% 4 6% 8% 26%	6690
	11th to 20th	Day	16% 7% 3 7% 5% 5% 5% 5% 7% 8% 33%	6360
	21st to end	Day	14% 6% 2 6% 4 4 5% 4 6% 8% 40%	6926
August	1st to 10th	Day	17% 8% 2 7% 5% 5% 6% 5% 7% 9% 30%	4466
	11th to 20th	Day	19% 8% 3 8% 5% 5% 6% 4 7% 7% 27%	4175
	21st to end	Day	21% 8% 3 6% 4 4 4 3 5% 6% 36%	4576
September	1st to 10th	Day	19% 7% 2 6% 4 4 4 3 5% 7% 38%	2385
	11th to 20th	Day	19% 7% 2 5% 3 2 3 3 5% 6% 45%	2200
	21st to end	Day	22% 8% 2 5% 3 3 3 3 5% 6% 38%	2200
October	1st to 10th	Day	18% 12% 3 7% 3 4 3 4 4 7% 34%	2190
	11th to 20th	Day	23% 15% 3 8% 4 4 3 3 4 6% 26%	1850
	21st to end	Day	27% 15% 3 8% 4 4 3 3 4 6% 23%	1980
November	1st to 10th	Day	18% 19% 3 8% 5% 5% 3 3 5% 4 27%	1851
	11th to 20th	Day	19% 17% 6% 11% 5% 4 3 3 4 4 24%	1837
	21st to end	Day	19% 21% 6% 12% 4 4 3 2 4 4 20%	1528
December	1st to 10th	Day	16% 17% 5% 14% 7% 5% 5% 3 4 4 19%	2350
	11th to 20th	Day	16% 17% 6% 12% 7% 4 3 2 3 4 24%	2688
	21st to end	Day	17% 17% 6% 12% 6% 4 4 3 4 5% 23%	3553
January	1st to 10th	Night	10% 18% 8% 14% 8% 6% 5% 4 4 5% 20%	8296
	11th to 20th	Night	8% 18% 8% 24% 10% 6% 4 3 3 3 14%	8235
	21st to end	Night	5% 9% 7% 17% 8% 7% 7% 4 6% 6% 25%	9057
February	1st to 10th	Night	9% 15% 6% 14% 8% 5% 5% 3 4 5% 26%	2888
	11th to 20th	Night	11% 18% 7% 13% 7% 5% 4 3 4 4 24%	2520
	21st to end	Night	12% 17% 5% 10% 6% 5% 4 3 3 5% 30%	2076
March	1st to 10th	Night	18% 16% 4 10% 6% 4 5% 3 4 5% 25%	5484
	11th to 20th	Night	12% 16% 5% 10% 6% 6% 6% 5% 5% 6% 22%	5203
	21st to end	Night	17% 17% 5% 10% 5% 4 3 3 4 4 28%	5243
April	1st to 10th	Night	21% 17% 5% 7% 5% 3 3 3 4 4 28%	2000
	11th to 20th	Night	19% 12% 3 8% 4 5% 4 4 6% 6% 30%	1837
	21st to end	Night	23% 13% 4 7% 5% 3 3 2 4 4 32%	1800
May	1st to 10th	Night	23% 11% 3 7% 4 4 5% 4 5% 6% 28%	4054
	11th to 20th	Night	23% 10% 3 7% 5% 4 5% 3 4 6% 30%	3604
	21st to end	Night	18% 10% 2 6% 4 4 4 4 5% 8% 34%	3629
June	1st to 10th	Night	22% 10% 3 6% 5% 6% 5% 4 4 6% 28%	1400
	11th to 20th	Night	16% 10% 3 7% 4 5% 4 3 5% 7% 36%	1400
	21st to end	Night	21% 9% 4 8% 4 4 5% 4 4 8% 29%	1400
July	1st to 10th	Night	15% 10% 4 8% 5% 5% 6% 4 5% 8% 30%	3281
	11th to 20th	Night	22% 9% 2 6% 3 4 5% 3 5% 7% 33%	3600
	21st to end	Night	13% 7% 2 6% 5% 5% 5% 4 6% 8% 39%	3926
August	1st to 10th	Night	20% 7% 3 7% 4 4 5% 3 5% 7% 34%	2652
	11th to 20th	Night	17% 9% 3 9% 6% 5% 5% 4 5% 7% 29%	2872
	21st to end	Night	19% 9% 2 6% 4 4 4 3 5% 6% 38%	3319
September	1st to 10th	Night	19% 7% 3 6% 4 4 4 4 4 6% 39%	2015
	11th to 20th	Night	19% 7% 3 6% 3 3 3 3 4 6% 43%	2200
	21st to end	Night	21% 8% 2 6% 4 3 4 3 4 4 41%	2200
October	1st to 10th	Night	19% 11% 2 6% 3 3 4 3 5% 5% 38%	2210
	11th to 20th	Night	24% 13% 3 8% 4 4 4 3 4 5% 29%	2547
	21st to end	Night	23% 16% 4 6% 4 4 4 3 4 6% 26%	2860
November	1st to 10th	Night	20% 16% 4 8% 5% 5% 4 3 4 5% 26%	2667
	11th to 20th	Night	17% 15% 5% 11% 5% 4 4 3 4 5% 27%	2780
	21st to end	Night	17% 20% 7% 12% 5% 4 4 3 3 4 21%	3087
December	1st to 10th	Night	13% 15% 8% 18% 9% 6% 5% 3 4 4 15%	5060
	11th to 20th	Night	16% 18% 6% 12% 8% 5% 4 3 3 4 21%	5741
	21st to end	Night	16% 19% 6% 12% 6% 4 3 3 3 3 26%	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	61% 8% 7% 17% 7%	4588
	11th to 20th	Day	73% 5% 5% 10% 6% 1	4680
	21st to end	Day	53% 6% 8% 17% 15% 1	5124
February	1st to 10th	Day	64% 6% 7% 13% 9% 2	1731
	11th to 20th	Day	64% 5% 9% 13% 8% 1	1992
	21st to end	Day	60% 4 7% 18% 8% 3	1730
March	1st to 10th	Day	65% 5% 6% 10% 10% 3	4579
	11th to 20th	Day	59% 6% 14% 13% 8% 1	4911
	21st to end	Day	61% 4 5% 15% 12% 3	5687
April	1st to 10th	Day	62% 5% 9% 13% 9% 2	2400
	11th to 20th	Day	54% 5% 8% 20% 12% 2	2512
	21st to end	Day	56% 5% 9% 16% 11% 3	2600
May	1st to 10th	Day	60% 6% 7% 16% 10% 1	5897
	11th to 20th	Day	57% 8% 12% 16% 5% 2	6322
	21st to end	Day	54% 7% 10% 18% 9% 1	7260
June	1st to 10th	Day	55% 8% 11% 19% 7% 1	3000
	11th to 20th	Day	50% 7% 14% 19% 9% 1	3000
	21st to end	Day	59% 7% 11% 15% 7%	3000
July	1st to 10th	Day	53% 8% 13% 19% 7%	6617
	11th to 20th	Day	44% 9% 19% 24% 4	6285
	21st to end	Day	40% 7% 18% 28% 8%	6728
August	1st to 10th	Day	47% 9% 19% 19% 5%	4452
	11th to 20th	Day	53% 9% 18% 16% 4	4214
	21st to end	Day	47% 8% 16% 18% 11% 1	4576
September	1st to 10th	Day	45% 7% 15% 23% 10%	2385
	11th to 20th	Day	40% 6% 14% 28% 12%	2200
	21st to end	Day	46% 6% 12% 24% 11%	2200
October	1st to 10th	Day	53% 5% 11% 24% 7%	3567
	11th to 20th	Day	52% 6% 15% 22% 4	2988
	21st to end	Day	53% 6% 14% 19% 8%	3180
November	1st to 10th	Day	59% 6% 12% 17% 6%	1851
	11th to 20th	Day	63% 7% 8% 14% 7% 1	1837
	21st to end	Day	68% 7% 8% 13% 4	1528
December	1st to 10th	Day	67% 6% 9% 10% 8%	2350
	11th to 20th	Day	63% 6% 8% 15% 8%	2688
	21st to end	Day	65% 4 8% 10% 12% 2	3553
January	1st to 10th	Night	64% 7% 10% 13% 6%	8296
	11th to 20th	Night	73% 6% 6% 11% 5%	8280
	21st to end	Night	53% 7% 9% 16% 14% 1	9057
February	1st to 10th	Night	59% 6% 8% 16% 10% 1	2888
	11th to 20th	Night	62% 5% 9% 14% 10% 1	2522
	21st to end	Night	55% 5% 7% 19% 12% 1	2076
March	1st to 10th	Night	61% 5% 7% 13% 13% 1	5494
	11th to 20th	Night	57% 9% 14% 12% 6% 1	5204
	21st to end	Night	60% 4 5% 18% 13% 1	5243
April	1st to 10th	Night	59% 5% 7% 15% 11% 3	2000
	11th to 20th	Night	51% 6% 9% 20% 12% 1	1837
	21st to end	Night	57% 5% 7% 18% 12% 2	1800
May	1st to 10th	Night	54% 7% 10% 18% 11% 1	4060
	11th to 20th	Night	53% 7% 12% 21% 7%	3605
	21st to end	Night	45% 9% 14% 20% 12% 1	3630
June	1st to 10th	Night	54% 7% 13% 18% 7%	1400
	11th to 20th	Night	46% 7% 13% 22% 11% 2	1400
	21st to end	Night	53% 8% 13% 16% 9% 1	1400
July	1st to 10th	Night	49% 8% 19% 20% 4	3244
	11th to 20th	Night	48% 7% 20% 23% 3	3552
	21st to end	Night	39% 8% 23% 22% 8%	3809
August	1st to 10th	Night	47% 8% 17% 24% 4	2642
	11th to 20th	Night	49% 11% 18% 16% 5%	2899
	21st to end	Night	45% 7% 15% 21% 11% 2	3319
September	1st to 10th	Night	43% 8% 13% 26% 10% 1	2015
	11th to 20th	Night	43% 6% 16% 26% 9%	2200
	21st to end	Night	45% 7% 11% 25% 12% 1	2200
October	1st to 10th	Night	46% 5% 12% 29% 8%	3613
	11th to 20th	Night	53% 5% 12% 24% 5%	4148
	21st to end	Night	50% 6% 17% 18% 9%	4610
November	1st to 10th	Night	57% 7% 11% 18% 6%	2667
	11th to 20th	Night	58% 7% 11% 15% 9% 1	2780
	21st to end	Night	65% 6% 11% 13% 4	3087
December	1st to 10th	Night	67% 8% 10% 12% 3	5060
	11th to 20th	Night	66% 5% 7% 15% 7%	5742
	21st to end	Night	63% 4 7% 13% 12% 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	27% 30% 35% 7% 1	220
	11th to 20th	Day	30% 27% 30% 10% 3	220
	21st to end	Day	20% 32% 34% 10% 4 1	242
February	1st to 10th	Day	23% 31% 31% 10% 5%	271
	11th to 20th	Day	23% 31% 34% 10% 1	502
	21st to end	Day	22% 31% 31% 13% 2	446
March	1st to 10th	Day	29% 26% 29% 12% 3	540
	11th to 20th	Day	28% 25% 31% 12% 4 1	528
	21st to end	Day	26% 28% 27% 13% 5% 1	550
April	1st to 10th	Day	34% 24% 25% 13% 4	500
	11th to 20th	Day	29% 26% 27% 14% 2 1	492
	21st to end	Day	31% 22% 31% 11% 3 2	500
May	1st to 10th	Day	29% 19% 34% 14% 3 1	503
	11th to 20th	Day	27% 15% 34% 18% 6% 1	527
	21st to end	Day	23% 19% 36% 18% 4	702
June	1st to 10th	Day	25% 16% 36% 16% 7%	730
	11th to 20th	Day	23% 17% 29% 23% 7%	730
	21st to end	Day	27% 15% 29% 22% 6% 1	730
July	1st to 10th	Day	21% 15% 35% 21% 7%	670
	11th to 20th	Day	20% 17% 39% 18% 6%	524
	21st to end	Day	18% 15% 40% 21% 6%	576
August	1st to 10th	Day	18% 15% 33% 23% 8% 2	526
	11th to 20th	Day	18% 13% 32% 24% 11% 1	519
	21st to end	Day	20% 17% 29% 21% 9% 3	583
September	1st to 10th	Day	21% 18% 30% 20% 9% 2	530
	11th to 20th	Day	21% 14% 32% 20% 10% 3	530
	21st to end	Day	20% 17% 33% 18% 8% 4	530
October	1st to 10th	Day	23% 19% 28% 20% 7% 2	524
	11th to 20th	Day	30% 21% 27% 15% 7% 1	420
	21st to end	Day	33% 26% 28% 10% 3	462
November	1st to 10th	Day	35% 20% 31% 12% 3	425
	11th to 20th	Day	27% 24% 27% 15% 6%	430
	21st to end	Day	32% 28% 30% 9% 1	278
December	1st to 10th	Day	29% 21% 32% 13% 3 1	220
	11th to 20th	Day	33% 29% 28% 9% 1	220
	21st to end	Day	32% 26% 27% 14% 1	242
January	1st to 10th	Night	23% 29% 35% 12% 2	852
	11th to 20th	Night	21% 27% 32% 16% 2	840
	21st to end	Night	15% 26% 37% 19% 3	924
February	1st to 10th	Night	16% 28% 36% 15% 4	840
	11th to 20th	Night	23% 26% 35% 13% 2	823
	21st to end	Night	23% 22% 35% 16% 3	692
March	1st to 10th	Night	24% 22% 36% 15% 3	840
	11th to 20th	Night	23% 23% 35% 12% 5% 1	829
	21st to end	Night	23% 20% 31% 21% 5%	880
April	1st to 10th	Night	29% 20% 31% 16% 4	800
	11th to 20th	Night	26% 17% 33% 19% 5%	653
	21st to end	Night	31% 14% 31% 19% 6% 1	600
May	1st to 10th	Night	26% 13% 32% 23% 6% 1	600
	11th to 20th	Night	25% 10% 29% 27% 9%	410
	21st to end	Night	24% 12% 32% 24% 7%	433
June	1st to 10th	Night	25% 10% 30% 30% 6%	400
	11th to 20th	Night	17% 10% 30% 33% 9%	400
	21st to end	Night	22% 12% 32% 27% 8% 1	400
July	1st to 10th	Night	16% 10% 39% 25% 9%	390
	11th to 20th	Night	18% 9% 34% 30% 9% 1	388
	21st to end	Night	16% 6% 31% 37% 9% 1	438
August	1st to 10th	Night	16% 7% 32% 30% 15% 1	438
	11th to 20th	Night	18% 8% 30% 32% 12% 1	592
	21st to end	Night	17% 10% 31% 29% 10% 2	717
September	1st to 10th	Night	20% 10% 32% 26% 11% 1	800
	11th to 20th	Night	20% 11% 30% 26% 12% 1	800
	21st to end	Night	22% 13% 29% 25% 12%	800
October	1st to 10th	Night	22% 17% 30% 23% 8% 1	800
	11th to 20th	Night	25% 20% 28% 19% 8% 1	800
	21st to end	Night	28% 21% 31% 15% 5%	880
November	1st to 10th	Night	31% 22% 28% 16% 3	820
	11th to 20th	Night	24% 25% 26% 18% 6% 1	868
	21st to end	Night	29% 24% 29% 15% 3 1	950
December	1st to 10th	Night	28% 21% 32% 14% 4	950
	11th to 20th	Night	27% 26% 28% 15% 4	950
	21st to end	Night	28% 27% 26% 16% 3	1045

Page generated at 2026-03-15 02:23:54. Version ac07

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