Little Point Sable
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Point Sable clear sky chart from 2005-11-06 to 2024-11-04.

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	13% 11% 4 9% 5% 4 4 3 5% 7% 35%	101336
	Night	14% 14% 5% 10% 5% 4 4 3 4 6% 30%	97756
Transparency	Day	46% 7% 13% 21% 12% 1	104894
	Night	53% 6% 11% 18% 10% 1	102339
Seeing	Day	16% 7% 22% 31% 19% 5%	15896
	Night	20% 8% 24% 30% 15% 3	25746

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	13% 30% 12% 16% 6% 4 3 2 2 2 8%	2527
	11th to 20th	Day	13% 19% 10% 20% 14% 10% 4 2 2 2 5%	2530
	21st to end	Day	18% 23% 10% 15% 7% 6% 5% 2 3 3 9%	2783
February	1st to 10th	Day	11% 16% 7% 16% 13% 6% 4 3 4 5% 15%	1690
	11th to 20th	Day	12% 16% 8% 19% 9% 5% 4 2 3 4 17%	1848
	21st to end	Day	13% 15% 7% 14% 7% 7% 4 3 4 5% 20%	1570
March	1st to 10th	Day	12% 12% 5% 9% 5% 5% 5% 4 5% 5% 34%	3120
	11th to 20th	Day	11% 9% 8% 12% 5% 4 3 3 4 6% 34%	3315
	21st to end	Day	19% 12% 6% 11% 5% 4 3 3 5% 5% 27%	4059
April	1st to 10th	Day	17% 13% 4 6% 5% 4 3 4 4 7% 33%	2280
	11th to 20th	Day	19% 10% 3 6% 4 4 4 3 5% 5% 36%	2282
	21st to end	Day	15% 10% 2 7% 5% 4 5% 4 5% 7% 37%	2470
May	1st to 10th	Day	13% 8% 3 6% 4 4 4 3 6% 8% 41%	4082
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 5% 10% 43%	4257
	21st to end	Day	9% 7% 2 6% 4 4 4 4 6% 9% 46%	4824
June	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 5% 7% 47%	2660
	11th to 20th	Day	12% 5% 2 5% 4 3 4 4 6% 9% 46%	2660
	21st to end	Day	10% 6% 2 5% 4 3 5% 3 6% 9% 46%	2660
July	1st to 10th	Day	14% 7% 2 6% 4 3 4 4 6% 8% 41%	4440
	11th to 20th	Day	5% 4 1 4 3 3 4 3 6% 9% 58%	4440
	21st to end	Day	7% 5% 2 5% 4 4 4 3 7% 9% 50%	4813
August	1st to 10th	Day	9% 5% 2 6% 4 4 6% 4 7% 9% 43%	4276
	11th to 20th	Day	11% 4 2 5% 3 3 3 3 5% 7% 53%	4024
	21st to end	Day	9% 6% 2 6% 4 5% 5% 4 6% 7% 47%	4180
September	1st to 10th	Day	12% 6% 2 6% 5% 4 3 3 5% 6% 47%	2280
	11th to 20th	Day	12% 5% 2 6% 3 3 4 4 5% 7% 49%	2101
	21st to end	Day	14% 8% 3 6% 4 4 5% 4 5% 7% 41%	2090
October	1st to 10th	Day	15% 7% 3 6% 4 4 3 3 6% 6% 42%	2090
	11th to 20th	Day	24% 13% 3 8% 5% 5% 4 4 6% 7% 23%	1814
	21st to end	Day	24% 13% 4 8% 5% 4 4 3 5% 6% 24%	1881
November	1st to 10th	Day	17% 14% 3 8% 6% 4 4 2 4 6% 32%	1699
	11th to 20th	Day	14% 25% 6% 11% 5% 4 4 3 5% 6% 17%	1710
	21st to end	Day	20% 22% 8% 12% 5% 3 3 2 3 5% 17%	1660
December	1st to 10th	Day	15% 25% 12% 16% 6% 4 3 2 3 3 12%	1520
	11th to 20th	Day	15% 24% 10% 15% 7% 3 4 2 4 4 10%	1918
	21st to end	Day	18% 24% 11% 14% 7% 5% 3 3 3 4 9%	2783
January	1st to 10th	Night	15% 27% 11% 15% 7% 4 2 2 2 3 12%	4428
	11th to 20th	Night	13% 20% 10% 21% 10% 11% 3 2 2 2 7%	4440
	21st to end	Night	16% 25% 10% 17% 8% 6% 4 1 2 3 8%	4884
February	1st to 10th	Night	11% 19% 6% 17% 11% 5% 4 3 3 4 17%	2485
	11th to 20th	Night	13% 15% 8% 17% 10% 6% 3 2 4 4 18%	2218
	21st to end	Night	15% 16% 6% 13% 7% 4 4 3 5% 5% 22%	1884
March	1st to 10th	Night	16% 10% 4 9% 5% 4 4 2 4 6% 37%	3733
	11th to 20th	Night	9% 11% 4 11% 5% 4 3 4 5% 6% 38%	3645
	21st to end	Night	16% 11% 4 13% 5% 6% 4 3 5% 5% 27%	3599
April	1st to 10th	Night	16% 13% 4 8% 4 4 3 3 6% 7% 32%	1900
	11th to 20th	Night	19% 10% 3 6% 4 4 4 3 5% 5% 36%	1847
	21st to end	Night	18% 9% 3 6% 5% 5% 3 4 6% 5% 37%	1710
May	1st to 10th	Night	13% 8% 3 8% 5% 5% 4 4 6% 7% 37%	2813
	11th to 20th	Night	13% 8% 3 6% 5% 5% 5% 5% 6% 8% 37%	2640
	21st to end	Night	17% 9% 3 7% 4 3 4 3 5% 7% 40%	2743
June	1st to 10th	Night	11% 7% 2 5% 4 4 4 4 6% 7% 44%	1520
	11th to 20th	Night	11% 5% 2 6% 4 4 4 3 5% 10% 45%	1520
	21st to end	Night	9% 6% 2 5% 5% 3 5% 5% 7% 9% 45%	1520
July	1st to 10th	Night	11% 8% 3 6% 5% 4 5% 5% 5% 7% 41%	2530
	11th to 20th	Night	6% 4 1 5% 4 4 4 4 5% 8% 56%	2530
	21st to end	Night	6% 5% 2 7% 5% 3 3 3 6% 7% 50%	2750
August	1st to 10th	Night	10% 5% 2 5% 4 4 5% 4 7% 8% 45%	2657
	11th to 20th	Night	10% 7% 2 5% 3 4 3 3 5% 7% 52%	2803
	21st to end	Night	9% 6% 2 6% 5% 4 5% 4 6% 8% 47%	3476
September	1st to 10th	Night	12% 5% 2 5% 5% 4 4 3 4 6% 49%	1900
	11th to 20th	Night	12% 5% 2 4 3 3 4 3 5% 7% 53%	2059
	21st to end	Night	15% 7% 2 5% 5% 5% 5% 3 5% 6% 42%	2090
October	1st to 10th	Night	18% 6% 2 5% 3 3 4 3 4 7% 44%	2090
	11th to 20th	Night	22% 11% 3 8% 5% 4 4 2 4 5% 31%	2363
	21st to end	Night	25% 13% 3 7% 4 4 4 3 5% 5% 26%	2717
November	1st to 10th	Night	15% 15% 4 8% 5% 4 3 3 4 5% 33%	2452
	11th to 20th	Night	16% 24% 6% 11% 4 5% 4 3 4 4 19%	2470
	21st to end	Night	19% 22% 7% 9% 5% 4 3 2 4 5% 20%	2517
December	1st to 10th	Night	16% 27% 10% 13% 6% 4 3 2 3 3 12%	2660
	11th to 20th	Night	17% 23% 10% 14% 6% 4 4 3 4 4 12%	3279
	21st to end	Night	23% 24% 8% 11% 5% 4 4 3 4 4 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	82% 6% 6% 5% 1	2528
	11th to 20th	Day	88% 5% 3 3	2530
	21st to end	Day	80% 7% 8% 3 1	2783
February	1st to 10th	Day	71% 8% 8% 11% 2	1690
	11th to 20th	Day	70% 6% 9% 10% 4	1858
	21st to end	Day	65% 7% 12% 11% 4	1570
March	1st to 10th	Day	47% 9% 16% 20% 8%	3120
	11th to 20th	Day	46% 10% 16% 19% 9% 1	3315
	21st to end	Day	56% 7% 12% 19% 7% 1	4059
April	1st to 10th	Day	50% 6% 13% 20% 10%	2280
	11th to 20th	Day	46% 7% 10% 20% 14% 2	2282
	21st to end	Day	45% 7% 14% 19% 13% 2	2470
May	1st to 10th	Day	38% 8% 13% 24% 14% 3	4120
	11th to 20th	Day	35% 10% 14% 22% 16% 3	4261
	21st to end	Day	33% 9% 13% 23% 20% 2	4837
June	1st to 10th	Day	37% 6% 11% 26% 18% 2	2660
	11th to 20th	Day	34% 8% 14% 25% 19% 1	2660
	21st to end	Day	35% 9% 16% 23% 16% 1	2660
July	1st to 10th	Day	40% 6% 14% 24% 12% 2	4371
	11th to 20th	Day	23% 7% 17% 33% 18% 2	4365
	21st to end	Day	29% 8% 16% 24% 21% 2	4662
August	1st to 10th	Day	34% 7% 15% 29% 14% 1	4261
	11th to 20th	Day	30% 6% 16% 32% 14% 1	4063
	21st to end	Day	34% 7% 16% 25% 18% 1	4179
September	1st to 10th	Day	35% 8% 15% 26% 15% 2	2280
	11th to 20th	Day	33% 7% 15% 31% 13% 1	2101
	21st to end	Day	40% 8% 14% 27% 12%	2090
October	1st to 10th	Day	27% 4 10% 38% 18% 2	3480
	11th to 20th	Day	47% 7% 12% 22% 12%	2991
	21st to end	Day	52% 5% 17% 17% 8%	3081
November	1st to 10th	Day	53% 7% 11% 19% 9% 1	1699
	11th to 20th	Day	68% 6% 12% 10% 4	1710
	21st to end	Day	71% 5% 13% 9% 3	1660
December	1st to 10th	Day	79% 6% 7% 6% 2	1520
	11th to 20th	Day	77% 5% 11% 5% 1	1915
	21st to end	Day	80% 7% 7% 5% 1	2783
January	1st to 10th	Night	78% 6% 8% 7% 1	4428
	11th to 20th	Night	86% 5% 4 3 1	4440
	21st to end	Night	82% 7% 8% 3	4884
February	1st to 10th	Night	72% 5% 7% 10% 5% 1	2485
	11th to 20th	Night	69% 6% 8% 12% 4	2219
	21st to end	Night	64% 6% 11% 13% 6%	1884
March	1st to 10th	Night	48% 7% 16% 23% 6%	3733
	11th to 20th	Night	43% 9% 12% 23% 11% 2	3645
	21st to end	Night	54% 9% 10% 18% 8% 1	3599
April	1st to 10th	Night	50% 7% 11% 18% 13% 1	1900
	11th to 20th	Night	49% 6% 7% 19% 15% 3	1847
	21st to end	Night	46% 6% 11% 21% 13% 4	1710
May	1st to 10th	Night	44% 7% 13% 19% 13% 4	2840
	11th to 20th	Night	40% 9% 12% 23% 13% 2	2641
	21st to end	Night	44% 6% 10% 19% 15% 7%	2751
June	1st to 10th	Night	36% 7% 13% 26% 15% 3	1520
	11th to 20th	Night	34% 7% 13% 23% 19% 3	1520
	21st to end	Night	32% 9% 16% 24% 15% 4	1520
July	1st to 10th	Night	42% 6% 11% 23% 13% 6%	2490
	11th to 20th	Night	25% 5% 14% 33% 18% 3	2482
	21st to end	Night	31% 7% 14% 20% 26% 2	2662
August	1st to 10th	Night	34% 6% 15% 25% 19% 1	2648
	11th to 20th	Night	32% 5% 11% 32% 19% 1	2830
	21st to end	Night	34% 7% 11% 24% 22% 2	3476
September	1st to 10th	Night	36% 7% 11% 25% 19% 2	1900
	11th to 20th	Night	30% 6% 12% 35% 14% 2	2059
	21st to end	Night	43% 7% 12% 26% 12% 1	2090
October	1st to 10th	Night	34% 4 10% 32% 18% 1	3480
	11th to 20th	Night	44% 5% 12% 25% 14% 1	3925
	21st to end	Night	48% 5% 12% 23% 11%	4467
November	1st to 10th	Night	52% 6% 11% 19% 11% 1	2452
	11th to 20th	Night	68% 6% 10% 10% 5%	2470
	21st to end	Night	67% 5% 14% 11% 2 1	2517
December	1st to 10th	Night	78% 6% 7% 7% 3	2660
	11th to 20th	Night	75% 8% 9% 5% 2	3281
	21st to end	Night	76% 7% 10% 6% 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	19% 12% 34% 27% 6% 2	270
	11th to 20th	Day	23% 12% 34% 25% 6%	270
	21st to end	Day	24% 10% 30% 28% 7%	297
February	1st to 10th	Day	19% 14% 37% 20% 8% 3	270
	11th to 20th	Day	15% 18% 39% 24% 4	270
	21st to end	Day	21% 13% 41% 23% 2	225
March	1st to 10th	Day	17% 13% 41% 23% 6%	270
	11th to 20th	Day	19% 13% 28% 26% 14% 1	360
	21st to end	Day	25% 11% 25% 28% 9% 1	506
April	1st to 10th	Day	21% 10% 31% 31% 7%	460
	11th to 20th	Day	22% 11% 28% 25% 10% 4	452
	21st to end	Day	18% 7% 26% 33% 15% 1	460
May	1st to 10th	Day	19% 7% 23% 37% 13% 2	463
	11th to 20th	Day	15% 4 21% 33% 23% 4	585
	21st to end	Day	13% 3 17% 34% 26% 7%	734
June	1st to 10th	Day	10% 3 19% 40% 23% 4	680
	11th to 20th	Day	15% 2 18% 36% 25% 4	680
	21st to end	Day	13% 4 17% 38% 24% 4	680
July	1st to 10th	Day	7% 2 13% 34% 34% 9%	671
	11th to 20th	Day	8% 3 14% 39% 28% 8%	668
	21st to end	Day	7% 2 12% 41% 32% 6%	739
August	1st to 10th	Day	9% 2 13% 36% 28% 12%	594
	11th to 20th	Day	11% 3 12% 32% 31% 11%	479
	21st to end	Day	13% 4 15% 29% 31% 8%	539
September	1st to 10th	Day	13% 4 16% 34% 25% 7%	490
	11th to 20th	Day	10% 3 14% 30% 32% 11%	490
	21st to end	Day	15% 8% 21% 23% 25% 8%	490
October	1st to 10th	Day	17% 7% 23% 26% 20% 6%	490
	11th to 20th	Day	28% 10% 24% 29% 9%	328
	21st to end	Day	33% 8% 32% 21% 5% 1	330
November	1st to 10th	Day	22% 11% 28% 26% 11% 2	279
	11th to 20th	Day	23% 19% 32% 23% 4	270
	21st to end	Day	27% 13% 35% 21% 4	270
December	1st to 10th	Day	23% 19% 31% 20% 6% 1	270
	11th to 20th	Day	26% 19% 31% 17% 6% 1	270
	21st to end	Day	29% 16% 32% 16% 6%	297
January	1st to 10th	Night	23% 15% 32% 23% 6% 1	950
	11th to 20th	Night	27% 11% 33% 22% 6% 1	950
	21st to end	Night	21% 11% 34% 28% 7%	1045
February	1st to 10th	Night	20% 14% 33% 27% 6% 1	870
	11th to 20th	Night	18% 13% 35% 27% 6%	743
	21st to end	Night	24% 14% 32% 25% 4	628
March	1st to 10th	Night	19% 8% 31% 30% 10% 1	760
	11th to 20th	Night	17% 8% 31% 33% 10% 2	760
	21st to end	Night	20% 7% 25% 33% 13% 2	708
April	1st to 10th	Night	19% 9% 28% 33% 9% 1	570
	11th to 20th	Night	25% 6% 24% 31% 12% 2	563
	21st to end	Night	22% 4 23% 34% 16% 1	570
May	1st to 10th	Night	16% 5% 21% 41% 15% 2	570
	11th to 20th	Night	16% 4 17% 38% 23% 2	561
	21st to end	Night	14% 3 14% 36% 28% 5%	617
June	1st to 10th	Night	13% 2 15% 41% 26% 3	570
	11th to 20th	Night	13% 2 16% 38% 26% 5%	570
	21st to end	Night	11% 2 12% 41% 29% 4	570
July	1st to 10th	Night	9% 1 8% 36% 38% 8%	555
	11th to 20th	Night	7% 3 11% 37% 35% 7%	552
	21st to end	Night	9% 2 10% 40% 34% 6%	624
August	1st to 10th	Night	8% 2 11% 39% 33% 7%	567
	11th to 20th	Night	10% 2 10% 35% 33% 9%	564
	21st to end	Night	13% 3 13% 33% 34% 4	627
September	1st to 10th	Night	14% 3 15% 35% 25% 7%	570
	11th to 20th	Night	13% 4 12% 33% 30% 8%	729
	21st to end	Night	18% 6% 19% 27% 24% 7%	760
October	1st to 10th	Night	21% 5% 20% 29% 21% 3	760
	11th to 20th	Night	29% 10% 22% 26% 11% 1	760
	21st to end	Night	31% 11% 25% 24% 7% 1	836
November	1st to 10th	Night	24% 10% 25% 29% 11% 1	755
	11th to 20th	Night	27% 15% 28% 24% 6%	760
	21st to end	Night	29% 12% 31% 23% 6%	807
December	1st to 10th	Night	29% 15% 31% 21% 3	950
	11th to 20th	Night	28% 16% 32% 21% 3 1	950
	21st to end	Night	31% 15% 33% 20% 2	1045

Page generated at 2024-11-01 22:47:43. Version ac07

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