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 2024-12-06.

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	18% 12% 4 9% 5% 5% 4 4 5% 6% 29%	101717
	Night	17% 14% 4 9% 5% 5% 4 3 4 5% 28%	98019
Transparency	Day	55% 7% 12% 18% 8% 1	105187
	Night	55% 7% 12% 18% 8% 1	102639
Seeing	Day	25% 20% 32% 17% 6% 1	15567
	Night	23% 19% 31% 20% 6% 1	23930

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% 17% 7% 16% 8% 5% 5% 3 4 5% 17%	2468
	11th to 20th	Day	10% 15% 6% 19% 8% 7% 4 2 3 3 23%	2520
	21st to end	Day	8% 10% 7% 16% 8% 5% 4 4 4 5% 27%	2772
February	1st to 10th	Day	11% 17% 5% 13% 8% 7% 4 4 4 5% 21%	1565
	11th to 20th	Day	14% 17% 7% 12% 8% 5% 4 3 4 4 23%	1789
	21st to end	Day	11% 16% 6% 11% 7% 5% 4 3 4 5% 28%	1570
March	1st to 10th	Day	17% 16% 5% 10% 6% 5% 4 3 4 5% 25%	3116
	11th to 20th	Day	14% 23% 6% 11% 6% 4 4 3 3 4 21%	3379
	21st to end	Day	16% 15% 6% 10% 4 3 4 2 3 4 33%	3967
April	1st to 10th	Day	23% 16% 3 9% 5% 4 4 3 3 5% 26%	2280
	11th to 20th	Day	19% 15% 3 6% 4 3 4 3 3 5% 35%	2385
	21st to end	Day	22% 13% 3 8% 4 4 3 3 4 5% 30%	2470
May	1st to 10th	Day	20% 11% 3 8% 6% 5% 4 3 4 6% 30%	4106
	11th to 20th	Day	19% 10% 3 8% 6% 6% 6% 4 5% 7% 26%	4398
	21st to end	Day	17% 9% 3 8% 6% 5% 5% 4 6% 6% 29%	5050
June	1st to 10th	Day	23% 9% 3 7% 5% 5% 5% 5% 6% 7% 26%	2850
	11th to 20th	Day	22% 7% 2 6% 5% 4 5% 4 6% 6% 33%	2850
	21st to end	Day	24% 10% 3 9% 6% 5% 4 3 5% 6% 25%	2850
July	1st to 10th	Day	16% 9% 3 8% 6% 5% 5% 4 6% 8% 30%	4672
	11th to 20th	Day	17% 8% 3 7% 5% 5% 5% 5% 7% 8% 31%	4440
	21st to end	Day	15% 7% 2 6% 4 5% 5% 4 5% 7% 39%	4814
August	1st to 10th	Day	17% 8% 3 7% 5% 5% 6% 5% 7% 9% 28%	4329
	11th to 20th	Day	19% 8% 3 8% 6% 5% 6% 4 8% 7% 26%	4045
	21st to end	Day	21% 8% 3 6% 4 4 4 3 5% 6% 36%	4436
September	1st to 10th	Day	20% 8% 2 6% 4 4 4 3 5% 7% 38%	2266
	11th to 20th	Day	20% 7% 2 5% 3 2 3 3 5% 6% 44%	2090
	21st to end	Day	22% 9% 2 5% 3 3 3 3 5% 6% 37%	2090
October	1st to 10th	Day	19% 13% 3 7% 3 5% 3 4 4 7% 32%	2081
	11th to 20th	Day	24% 15% 3 8% 4 4 4 3 4 6% 25%	1758
	21st to end	Day	27% 15% 3 8% 4 4 3 3 4 5% 24%	1881
November	1st to 10th	Day	18% 19% 3 8% 5% 4 3 3 5% 4 28%	1761
	11th to 20th	Day	20% 17% 6% 10% 5% 4 3 3 4 4 24%	1750
	21st to end	Day	19% 21% 5% 12% 4 4 3 2 4 4 20%	1455
December	1st to 10th	Day	21% 20% 7% 11% 6% 4 4 3 3 4 18%	1365
	11th to 20th	Day	17% 18% 5% 11% 6% 5% 4 2 3 3 24%	1668
	21st to end	Day	20% 17% 6% 12% 6% 4 4 3 3 4 22%	2431
January	1st to 10th	Night	12% 19% 9% 14% 8% 6% 5% 3 3 3 19%	4464
	11th to 20th	Night	10% 16% 6% 17% 10% 6% 4 3 4 3 20%	4440
	21st to end	Night	8% 13% 6% 15% 7% 7% 5% 4 6% 6% 24%	4884
February	1st to 10th	Night	10% 15% 6% 13% 8% 5% 5% 3 4 5% 24%	2614
	11th to 20th	Night	11% 18% 7% 14% 7% 5% 4 3 4 4 23%	2274
	21st to end	Night	13% 17% 5% 10% 6% 5% 5% 3 3 5% 28%	1884
March	1st to 10th	Night	20% 15% 4 8% 5% 4 6% 4 4 5% 27%	3724
	11th to 20th	Night	13% 20% 5% 11% 6% 6% 5% 4 4 4 23%	3580
	21st to end	Night	18% 16% 5% 10% 5% 4 4 2 4 4 30%	3663
April	1st to 10th	Night	21% 17% 5% 7% 5% 3 3 3 4 4 28%	1900
	11th to 20th	Night	20% 12% 3 7% 4 5% 4 4 6% 6% 31%	1744
	21st to end	Night	23% 13% 4 7% 5% 3 3 2 4 4 32%	1710
May	1st to 10th	Night	22% 10% 3 6% 4 4 4 4 6% 6% 32%	2834
	11th to 20th	Night	18% 10% 4 8% 6% 4 5% 3 5% 6% 31%	2510
	21st to end	Night	17% 7% 2 6% 4 5% 4 5% 6% 9% 35%	2532
June	1st to 10th	Night	22% 10% 4 6% 5% 6% 5% 4 5% 6% 27%	1330
	11th to 20th	Night	16% 10% 3 6% 4 5% 4 3 5% 7% 37%	1330
	21st to end	Night	21% 10% 4 8% 4 4 5% 4 5% 8% 29%	1330
July	1st to 10th	Night	12% 10% 4 9% 5% 5% 5% 4 5% 8% 32%	2292
	11th to 20th	Night	21% 9% 3 6% 4 5% 5% 4 5% 7% 32%	2520
	21st to end	Night	14% 8% 2 6% 4 4 5% 4 5% 9% 40%	2739
August	1st to 10th	Night	21% 8% 3 7% 4 4 5% 3 5% 7% 33%	2570
	11th to 20th	Night	17% 9% 3 9% 6% 5% 5% 4 6% 7% 27%	2782
	21st to end	Night	19% 9% 2 6% 4 4 4 3 5% 6% 38%	3217
September	1st to 10th	Night	19% 7% 3 5% 4 5% 4 4 4 6% 38%	1914
	11th to 20th	Night	20% 7% 3 6% 3 3 3 3 4 6% 42%	2090
	21st to end	Night	20% 8% 2 7% 4 3 4 3 4 4 41%	2090
October	1st to 10th	Night	19% 12% 3 7% 4 3 4 3 5% 5% 37%	2099
	11th to 20th	Night	25% 14% 3 8% 4 4 4 3 4 5% 28%	2419
	21st to end	Night	23% 15% 4 6% 4 4 4 3 4 6% 27%	2717
November	1st to 10th	Night	19% 15% 4 8% 5% 5% 4 3 4 6% 27%	2537
	11th to 20th	Night	17% 15% 5% 11% 5% 4 4 3 4 5% 28%	2647
	21st to end	Night	18% 19% 7% 11% 5% 4 4 3 4 4 21%	2940
December	1st to 10th	Night	19% 20% 7% 12% 6% 4 4 3 4 4 17%	2932
	11th to 20th	Night	17% 18% 6% 12% 6% 5% 4 3 4 4 20%	3531
	21st to end	Night	19% 21% 5% 11% 5% 3 3 3 3 3 25%	5236

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	66% 9% 9% 12% 4	2469
	11th to 20th	Day	66% 6% 5% 14% 8% 1	2520
	21st to end	Day	58% 9% 7% 15% 10% 1	2772
February	1st to 10th	Day	66% 6% 8% 11% 9% 1	1565
	11th to 20th	Day	66% 5% 9% 11% 8% 1	1798
	21st to end	Day	60% 4 7% 17% 8% 3	1570
March	1st to 10th	Day	62% 5% 8% 13% 9% 2	3119
	11th to 20th	Day	67% 5% 10% 11% 6% 1	3379
	21st to end	Day	56% 4 7% 17% 13% 3	3967
April	1st to 10th	Day	62% 5% 9% 13% 9% 2	2280
	11th to 20th	Day	53% 4 9% 20% 12% 2	2385
	21st to end	Day	56% 5% 9% 16% 12% 3	2470
May	1st to 10th	Day	55% 7% 9% 17% 11% 1	4120
	11th to 20th	Day	54% 8% 15% 17% 7%	4402
	21st to end	Day	51% 9% 10% 20% 10%	5050
June	1st to 10th	Day	55% 8% 11% 18% 6% 1	2850
	11th to 20th	Day	50% 7% 14% 19% 9% 1	2850
	21st to end	Day	60% 7% 10% 15% 7%	2850
July	1st to 10th	Day	51% 8% 14% 20% 7%	4599
	11th to 20th	Day	47% 9% 18% 22% 4	4365
	21st to end	Day	43% 8% 17% 24% 8%	4661
August	1st to 10th	Day	49% 9% 18% 19% 4	4315
	11th to 20th	Day	54% 9% 19% 14% 4	4084
	21st to end	Day	47% 8% 16% 18% 11% 1	4436
September	1st to 10th	Day	46% 7% 14% 22% 10%	2266
	11th to 20th	Day	41% 6% 14% 27% 12%	2090
	21st to end	Day	47% 6% 12% 24% 10%	2090
October	1st to 10th	Day	54% 5% 11% 23% 6%	3458
	11th to 20th	Day	53% 6% 15% 22% 4	2896
	21st to end	Day	53% 6% 14% 19% 8%	3081
November	1st to 10th	Day	59% 6% 12% 17% 6%	1761
	11th to 20th	Day	63% 6% 9% 14% 7% 1	1750
	21st to end	Day	68% 7% 9% 13% 4	1455
December	1st to 10th	Day	71% 5% 8% 12% 4	1365
	11th to 20th	Day	64% 5% 7% 16% 8% 1	1668
	21st to end	Day	67% 5% 8% 12% 7% 1	2431
January	1st to 10th	Night	67% 8% 8% 12% 5%	4464
	11th to 20th	Night	67% 6% 8% 14% 5%	4440
	21st to end	Night	58% 8% 8% 13% 11% 2	4884
February	1st to 10th	Night	60% 7% 9% 14% 10% 1	2614
	11th to 20th	Night	63% 5% 9% 13% 9% 1	2276
	21st to end	Night	56% 5% 7% 18% 12% 2	1884
March	1st to 10th	Night	59% 6% 9% 15% 9% 1	3734
	11th to 20th	Night	59% 9% 13% 12% 6% 1	3581
	21st to end	Night	59% 4 6% 19% 10% 2	3663
April	1st to 10th	Night	59% 5% 7% 14% 11% 3	1900
	11th to 20th	Night	50% 7% 8% 21% 13% 1	1744
	21st to end	Night	57% 5% 6% 18% 12% 2	1710
May	1st to 10th	Night	49% 8% 12% 21% 10% 1	2840
	11th to 20th	Night	51% 8% 13% 19% 9%	2511
	21st to end	Night	42% 10% 14% 20% 13%	2533
June	1st to 10th	Night	55% 7% 14% 18% 6%	1330
	11th to 20th	Night	46% 7% 13% 21% 11% 3	1330
	21st to end	Night	53% 8% 13% 16% 9% 1	1330
July	1st to 10th	Night	46% 9% 19% 21% 5%	2255
	11th to 20th	Night	49% 8% 19% 21% 4	2472
	21st to end	Night	38% 9% 24% 21% 8%	2651
August	1st to 10th	Night	48% 8% 16% 24% 3	2560
	11th to 20th	Night	50% 12% 18% 15% 4	2809
	21st to end	Night	44% 7% 15% 21% 11% 2	3217
September	1st to 10th	Night	44% 8% 13% 24% 10% 1	1914
	11th to 20th	Night	44% 6% 16% 25% 9%	2090
	21st to end	Night	45% 7% 11% 25% 11% 1	2090
October	1st to 10th	Night	47% 5% 12% 28% 7%	3502
	11th to 20th	Night	53% 5% 12% 24% 5%	4020
	21st to end	Night	49% 6% 17% 18% 9%	4467
November	1st to 10th	Night	57% 7% 12% 18% 6%	2537
	11th to 20th	Night	57% 7% 11% 16% 9% 1	2647
	21st to end	Night	65% 6% 11% 13% 4	2940
December	1st to 10th	Night	69% 6% 10% 11% 3	2932
	11th to 20th	Night	66% 5% 9% 13% 8%	3532
	21st to end	Night	64% 4 9% 14% 8% 1	5236

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	24% 30% 36% 7% 2 1	180
	11th to 20th	Day	30% 27% 31% 8% 3	180
	21st to end	Day	18% 31% 35% 12% 4 1	198
February	1st to 10th	Day	25% 32% 30% 8% 4	225
	11th to 20th	Day	23% 32% 34% 10% 1	428
	21st to end	Day	23% 32% 30% 13% 3	382
March	1st to 10th	Day	27% 24% 32% 13% 3	460
	11th to 20th	Day	25% 25% 32% 13% 5% 1	460
	21st to end	Day	25% 27% 28% 13% 5% 1	506
April	1st to 10th	Day	33% 24% 24% 14% 5%	460
	11th to 20th	Day	28% 26% 27% 15% 3 1	452
	21st to end	Day	30% 22% 32% 11% 3 2	460
May	1st to 10th	Day	27% 19% 35% 14% 3 1	463
	11th to 20th	Day	25% 15% 34% 19% 6% 1	487
	21st to end	Day	21% 20% 37% 17% 5%	651
June	1st to 10th	Day	25% 15% 36% 16% 7%	680
	11th to 20th	Day	22% 17% 29% 24% 8%	680
	21st to end	Day	27% 15% 29% 22% 7% 1	680
July	1st to 10th	Day	21% 14% 37% 21% 8%	623
	11th to 20th	Day	20% 16% 40% 18% 6%	484
	21st to end	Day	18% 14% 40% 22% 6%	532
August	1st to 10th	Day	20% 16% 32% 23% 8% 1	486
	11th to 20th	Day	18% 14% 32% 24% 11% 1	479
	21st to end	Day	20% 18% 28% 22% 9% 4	539
September	1st to 10th	Day	21% 18% 30% 19% 9% 3	490
	11th to 20th	Day	22% 13% 33% 20% 10% 2	490
	21st to end	Day	20% 17% 33% 18% 9% 4	490
October	1st to 10th	Day	23% 19% 27% 20% 8% 2	485
	11th to 20th	Day	31% 20% 28% 14% 7% 1	390
	21st to end	Day	32% 27% 27% 10% 4	429
November	1st to 10th	Day	34% 20% 31% 12% 3	395
	11th to 20th	Day	28% 24% 27% 16% 6% 1	400
	21st to end	Day	32% 27% 29% 10% 1	255
December	1st to 10th	Day	29% 18% 33% 16% 3 1	190
	11th to 20th	Day	32% 29% 28% 9% 1 1	180
	21st to end	Day	36% 25% 26% 12% 1	198
January	1st to 10th	Night	23% 28% 35% 12% 1	770
	11th to 20th	Night	22% 28% 32% 16% 2	760
	21st to end	Night	15% 25% 37% 19% 4	836
February	1st to 10th	Night	17% 29% 36% 14% 4	760
	11th to 20th	Night	22% 28% 35% 13% 3	743
	21st to end	Night	24% 23% 34% 16% 4	628
March	1st to 10th	Night	23% 21% 37% 16% 3	760
	11th to 20th	Night	22% 23% 35% 13% 6% 1	760
	21st to end	Night	22% 20% 30% 21% 6%	836
April	1st to 10th	Night	28% 19% 31% 17% 4	760
	11th to 20th	Night	26% 16% 32% 19% 5%	620
	21st to end	Night	30% 14% 30% 20% 6% 1	570
May	1st to 10th	Night	26% 13% 31% 23% 6% 1	570
	11th to 20th	Night	24% 11% 28% 28% 9% 1	389
	21st to end	Night	24% 13% 32% 24% 7%	411
June	1st to 10th	Night	25% 9% 30% 29% 7%	380
	11th to 20th	Night	17% 10% 31% 33% 10%	380
	21st to end	Night	22% 10% 31% 27% 8% 1	380
July	1st to 10th	Night	15% 10% 40% 26% 9%	370
	11th to 20th	Night	18% 9% 34% 30% 9% 1	368
	21st to end	Night	17% 6% 30% 37% 9% 1	416
August	1st to 10th	Night	16% 6% 32% 30% 14% 1	416
	11th to 20th	Night	19% 8% 29% 31% 12% 1	562
	21st to end	Night	17% 10% 31% 29% 11% 2	681
September	1st to 10th	Night	21% 10% 33% 25% 11% 1	760
	11th to 20th	Night	21% 10% 30% 26% 11% 1	760
	21st to end	Night	21% 13% 29% 24% 12%	760
October	1st to 10th	Night	22% 18% 29% 23% 8% 1	760
	11th to 20th	Night	26% 21% 28% 18% 7% 1	760
	21st to end	Night	28% 21% 31% 15% 5%	836
November	1st to 10th	Night	29% 22% 29% 16% 3	780
	11th to 20th	Night	24% 25% 26% 18% 6% 1	825
	21st to end	Night	28% 24% 29% 15% 3 1	900
December	1st to 10th	Night	28% 21% 32% 14% 5%	878
	11th to 20th	Night	26% 26% 28% 15% 4	850
	21st to end	Night	29% 27% 26% 15% 3	935

Page generated at 2024-12-03 06:45:09. Version ac07

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