Lookout Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lookout Point clear sky chart from 2005-11-06 to 2024-01-13.

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% 10% 4 7% 6% 3 5% 5% 5% 6% 32%	74722
	Night	18% 11% 4 7% 6% 3 4 4 5% 6% 31%	75018
Transparency	Day	52% 5% 11% 20% 10% 1	74427
	Night	55% 4 11% 19% 10% 1	74847
Seeing	Day	23% 14% 29% 21% 11% 3	13274
	Night	23% 11% 27% 27% 11% 1	22540

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% 17% 6% 11% 9% 4 4 4 3 4 21%	1517
	11th to 20th	Day	18% 17% 6% 9% 7% 4 5% 4 4 4 22%	1462
	21st to end	Day	14% 14% 6% 10% 8% 4 4 4 5% 4 25%	1691
February	1st to 10th	Day	13% 16% 5% 12% 9% 4 5% 5% 5% 6% 21%	1620
	11th to 20th	Day	14% 14% 6% 9% 7% 4 5% 4 4 6% 27%	1573
	21st to end	Day	19% 13% 5% 8% 6% 4 5% 5% 4 6% 25%	1432
March	1st to 10th	Day	15% 13% 5% 9% 7% 3 5% 4 5% 4 29%	1847
	11th to 20th	Day	14% 12% 5% 8% 9% 4 4 4 4 5% 31%	1980
	21st to end	Day	19% 8% 4 5% 6% 3 3 4 4 6% 38%	2255
April	1st to 10th	Day	22% 10% 4 5% 5% 3 4 5% 4 6% 30%	2160
	11th to 20th	Day	22% 8% 3 5% 5% 3 4 4 4 5% 36%	2134
	21st to end	Day	22% 9% 3 7% 6% 3 4 4 4 6% 33%	2316
May	1st to 10th	Day	20% 8% 3 6% 5% 3 5% 4 5% 6% 36%	2520
	11th to 20th	Day	17% 7% 3 6% 6% 3 4 4 5% 6% 37%	2478
	21st to end	Day	14% 6% 3 6% 7% 3 5% 5% 5% 8% 38%	2725
June	1st to 10th	Day	21% 6% 3 7% 6% 3 5% 5% 5% 7% 31%	2520
	11th to 20th	Day	15% 5% 2 5% 5% 3 6% 4 5% 8% 40%	2520
	21st to end	Day	16% 7% 3 7% 6% 4 6% 5% 6% 8% 33%	2520
July	1st to 10th	Day	12% 5% 3 5% 6% 4 6% 6% 6% 9% 40%	2520
	11th to 20th	Day	12% 6% 3 5% 5% 4 6% 7% 7% 8% 38%	2520
	21st to end	Day	11% 5% 3 6% 6% 3 6% 6% 7% 9% 38%	2744
August	1st to 10th	Day	11% 6% 2 6% 7% 5% 6% 5% 6% 8% 38%	2423
	11th to 20th	Day	12% 6% 3 6% 6% 4 5% 5% 6% 8% 39%	2303
	21st to end	Day	15% 6% 2 5% 4 3 5% 6% 7% 9% 37%	2404
September	1st to 10th	Day	14% 6% 3 5% 5% 3 3 5% 6% 8% 42%	2160
	11th to 20th	Day	14% 6% 3 5% 5% 3 5% 5% 5% 6% 44%	2160
	21st to end	Day	18% 6% 3 6% 5% 3 6% 5% 5% 7% 35%	1900
October	1st to 10th	Day	21% 8% 2 5% 6% 3 5% 5% 5% 6% 34%	1800
	11th to 20th	Day	26% 11% 3 7% 6% 4 5% 4 4 5% 26%	1800
	21st to end	Day	28% 10% 3 6% 6% 3 4 4 5% 6% 24%	1873
November	1st to 10th	Day	16% 11% 3 7% 6% 4 4 5% 5% 6% 33%	1607
	11th to 20th	Day	20% 12% 5% 9% 8% 4 5% 4 4 6% 23%	1520
	21st to end	Day	25% 16% 6% 8% 8% 4 5% 4 4 5% 16%	1520
December	1st to 10th	Day	22% 17% 6% 10% 8% 4 5% 4 4 4 16%	1520
	11th to 20th	Day	20% 16% 5% 9% 7% 4 4 4 3 6% 20%	1906
	21st to end	Day	27% 19% 5% 13% 5% 2 3 2 2 3 19%	2772
January	1st to 10th	Night	18% 19% 6% 11% 8% 4 5% 4 3 5% 16%	2649
	11th to 20th	Night	19% 15% 6% 11% 8% 3 4 4 4 4 21%	2560
	21st to end	Night	12% 15% 6% 9% 7% 4 5% 4 4 5% 28%	2664
February	1st to 10th	Night	14% 14% 7% 13% 8% 4 6% 5% 5% 5% 20%	2340
	11th to 20th	Night	14% 14% 6% 10% 7% 3 5% 4 5% 5% 27%	2273
	21st to end	Night	15% 13% 5% 11% 8% 3 4 4 4 6% 28%	1823
March	1st to 10th	Night	17% 13% 5% 7% 8% 4 5% 4 4 4 28%	2096
	11th to 20th	Night	15% 13% 5% 7% 5% 3 4 3 6% 6% 33%	1979
	21st to end	Night	16% 10% 4 7% 6% 3 4 3 4 6% 39%	2100
April	1st to 10th	Night	21% 11% 4 7% 6% 3 4 4 4 6% 30%	1800
	11th to 20th	Night	20% 10% 3 6% 5% 3 4 5% 4 6% 35%	1775
	21st to end	Night	21% 9% 4 8% 6% 3 4 4 5% 5% 31%	1658
May	1st to 10th	Night	21% 8% 4 5% 4 2 3 4 5% 6% 38%	1440
	11th to 20th	Night	20% 7% 2 5% 5% 3 4 4 5% 7% 39%	1415
	21st to end	Night	13% 5% 2 5% 5% 3 5% 5% 6% 8% 44%	1550
June	1st to 10th	Night	17% 6% 4 7% 5% 3 5% 5% 6% 7% 36%	1440
	11th to 20th	Night	14% 5% 3 5% 4 3 5% 5% 5% 8% 43%	1440
	21st to end	Night	16% 7% 2 5% 7% 3 5% 4 5% 8% 37%	1440
July	1st to 10th	Night	11% 4 2 4 5% 3 6% 5% 6% 8% 44%	1440
	11th to 20th	Night	13% 7% 2 5% 5% 3 4 6% 6% 8% 42%	1440
	21st to end	Night	9% 5% 2 5% 6% 3 6% 5% 8% 9% 43%	1574
August	1st to 10th	Night	10% 5% 2 4 6% 4 6% 6% 8% 7% 42%	1511
	11th to 20th	Night	11% 4 3 5% 5% 3 5% 4 5% 9% 44%	1598
	21st to end	Night	13% 5% 2 5% 6% 3 5% 5% 5% 8% 43%	1934
September	1st to 10th	Night	11% 6% 3 5% 5% 4 4 4 5% 8% 44%	1800
	11th to 20th	Night	16% 5% 2 5% 4 2 4 3 5% 7% 47%	1800
	21st to end	Night	19% 7% 3 6% 5% 3 3 4 3 6% 42%	2057
October	1st to 10th	Night	21% 8% 3 4 5% 3 4 4 4 7% 38%	2160
	11th to 20th	Night	23% 10% 3 7% 7% 3 4 4 5% 5% 28%	2160
	21st to end	Night	25% 12% 3 7% 6% 3 5% 3 5% 5% 26%	2482
November	1st to 10th	Night	19% 11% 3 6% 5% 3 4 5% 5% 6% 32%	2468
	11th to 20th	Night	19% 12% 4 8% 8% 4 5% 4 5% 6% 25%	2660
	21st to end	Night	23% 15% 6% 9% 5% 4 4 4 4 6% 19%	2660
December	1st to 10th	Night	22% 19% 6% 10% 8% 3 4 4 4 5% 16%	2660
	11th to 20th	Night	21% 18% 5% 8% 6% 2 4 3 4 4 23%	3288
	21st to end	Night	28% 19% 5% 10% 5% 2 3 3 3 3 17%	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	68% 4 8% 14% 6%	1518
	11th to 20th	Day	67% 4 9% 11% 9% 1	1462
	21st to end	Day	63% 4 7% 14% 10% 1	1691
February	1st to 10th	Day	64% 4 9% 17% 5% 1	1620
	11th to 20th	Day	59% 3 13% 15% 9% 1	1582
	21st to end	Day	61% 3 10% 15% 9% 1	1432
March	1st to 10th	Day	59% 4 9% 17% 10% 1	1850
	11th to 20th	Day	57% 3 10% 16% 11% 2	1980
	21st to end	Day	49% 3 9% 20% 13% 5%	2255
April	1st to 10th	Day	55% 3 7% 20% 12% 3	2160
	11th to 20th	Day	51% 4 6% 22% 15% 2	2134
	21st to end	Day	54% 3 7% 16% 15% 4	2316
May	1st to 10th	Day	49% 5% 9% 20% 14% 4	2520
	11th to 20th	Day	48% 4 8% 20% 18% 2	2482
	21st to end	Day	45% 5% 12% 20% 14% 3	2725
June	1st to 10th	Day	52% 5% 10% 20% 12% 1	2520
	11th to 20th	Day	42% 5% 12% 24% 14% 2	2520
	21st to end	Day	47% 7% 12% 21% 12% 1	2520
July	1st to 10th	Day	38% 6% 11% 28% 15% 1	2450
	11th to 20th	Day	39% 7% 15% 26% 12% 1	2445
	21st to end	Day	40% 7% 15% 29% 10%	2591
August	1st to 10th	Day	43% 7% 15% 23% 11%	2409
	11th to 20th	Day	41% 8% 17% 25% 8% 1	2303
	21st to end	Day	41% 6% 15% 25% 12% 1	2404
September	1st to 10th	Day	40% 6% 14% 29% 11%	2160
	11th to 20th	Day	41% 5% 11% 32% 10% 1	2160
	21st to end	Day	48% 5% 14% 25% 8%	1900
October	1st to 10th	Day	52% 4 11% 21% 11% 1	1800
	11th to 20th	Day	61% 4 13% 17% 5% 1	1800
	21st to end	Day	61% 4 13% 16% 5% 1	1873
November	1st to 10th	Day	51% 5% 15% 22% 7% 1	1607
	11th to 20th	Day	61% 5% 14% 13% 7% 1	1520
	21st to end	Day	72% 4 10% 9% 5%	1520
December	1st to 10th	Day	72% 4 9% 10% 4	1520
	11th to 20th	Day	66% 5% 10% 13% 7%	1906
	21st to end	Day	74% 2 7% 14% 3	2772
January	1st to 10th	Night	72% 4 9% 11% 4	2649
	11th to 20th	Night	68% 4 9% 12% 7% 1	2560
	21st to end	Night	58% 4 8% 18% 11%	2664
February	1st to 10th	Night	66% 4 9% 14% 6% 1	2340
	11th to 20th	Night	61% 4 9% 19% 7% 1	2275
	21st to end	Night	59% 3 9% 19% 9% 1	1823
March	1st to 10th	Night	59% 4 9% 16% 10% 2	2106
	11th to 20th	Night	53% 4 11% 17% 13% 2	1980
	21st to end	Night	48% 3 8% 21% 15% 5%	2100
April	1st to 10th	Night	56% 3 8% 18% 13% 2	1800
	11th to 20th	Night	50% 4 7% 22% 15% 2	1775
	21st to end	Night	56% 3 6% 16% 16% 2	1658
May	1st to 10th	Night	47% 5% 6% 22% 16% 5%	1440
	11th to 20th	Night	45% 4 7% 22% 18% 4	1416
	21st to end	Night	38% 6% 14% 21% 17% 3	1551
June	1st to 10th	Night	46% 6% 13% 25% 9% 1	1440
	11th to 20th	Night	39% 6% 11% 26% 15% 2	1440
	21st to end	Night	46% 5% 13% 21% 14% 1	1440
July	1st to 10th	Night	35% 7% 14% 24% 19% 2	1400
	11th to 20th	Night	38% 6% 13% 28% 14%	1392
	21st to end	Night	35% 7% 15% 30% 12%	1486
August	1st to 10th	Night	38% 8% 16% 24% 13%	1501
	11th to 20th	Night	35% 7% 19% 27% 11% 1	1598
	21st to end	Night	39% 5% 16% 28% 11% 1	1934
September	1st to 10th	Night	40% 5% 11% 29% 14% 1	1800
	11th to 20th	Night	38% 4 16% 33% 9% 1	1800
	21st to end	Night	44% 4 14% 30% 8%	2057
October	1st to 10th	Night	48% 4 12% 23% 13%	2160
	11th to 20th	Night	57% 6% 11% 19% 7%	2160
	21st to end	Night	61% 5% 12% 15% 8%	2482
November	1st to 10th	Night	53% 5% 14% 20% 9%	2468
	11th to 20th	Night	60% 5% 13% 15% 8% 1	2660
	21st to end	Night	67% 4 12% 14% 3	2660
December	1st to 10th	Night	71% 4 8% 12% 4	2660
	11th to 20th	Night	66% 3 9% 14% 7% 1	3288
	21st to end	Night	75% 3 7% 12% 4	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	23% 17% 29% 24% 6% 1	180
	11th to 20th	Day	30% 17% 33% 17% 4 1	166
	21st to end	Day	24% 18% 32% 17% 8% 1	224
February	1st to 10th	Day	30% 20% 35% 13% 2	240
	11th to 20th	Day	26% 24% 38% 11% 1	240
	21st to end	Day	33% 19% 32% 15% 1	298
March	1st to 10th	Day	25% 17% 34% 20% 4	420
	11th to 20th	Day	25% 18% 33% 18% 5% 1	420
	21st to end	Day	29% 18% 28% 18% 7% 1	462
April	1st to 10th	Day	32% 17% 28% 15% 8%	420
	11th to 20th	Day	33% 15% 21% 16% 11% 4	412
	21st to end	Day	30% 16% 29% 17% 7% 2	420
May	1st to 10th	Day	27% 14% 26% 22% 8% 3	423
	11th to 20th	Day	20% 18% 30% 19% 9% 4	447
	21st to end	Day	19% 15% 31% 21% 12% 3	485
June	1st to 10th	Day	25% 11% 30% 23% 10% 1	450
	11th to 20th	Day	18% 13% 25% 25% 15% 4	450
	21st to end	Day	18% 12% 29% 23% 15% 3	450
July	1st to 10th	Day	12% 6% 25% 36% 17% 3	445
	11th to 20th	Day	13% 7% 30% 30% 16% 5%	444
	21st to end	Day	13% 7% 31% 30% 15% 4	488
August	1st to 10th	Day	14% 7% 24% 30% 17% 7%	446
	11th to 20th	Day	14% 6% 23% 26% 21% 10%	439
	21st to end	Day	14% 11% 26% 25% 17% 7%	495
September	1st to 10th	Day	16% 8% 28% 24% 16% 9%	450
	11th to 20th	Day	17% 9% 23% 22% 19% 10%	450
	21st to end	Day	18% 12% 27% 21% 15% 7%	450
October	1st to 10th	Day	26% 12% 23% 20% 15% 4	450
	11th to 20th	Day	31% 17% 30% 15% 7% 1	450
	21st to end	Day	31% 15% 24% 22% 5% 1	441
November	1st to 10th	Day	26% 16% 32% 17% 8% 1	301
	11th to 20th	Day	26% 22% 34% 11% 5% 2	180
	21st to end	Day	32% 21% 31% 10% 4 2	180
December	1st to 10th	Day	30% 12% 38% 17% 3 1	180
	11th to 20th	Day	27% 27% 31% 12% 3 1	180
	21st to end	Day	32% 17% 32% 13% 6% 1	198
January	1st to 10th	Night	28% 13% 32% 22% 5%	760
	11th to 20th	Night	29% 14% 26% 23% 8%	732
	21st to end	Night	19% 12% 33% 28% 8% 1	792
February	1st to 10th	Night	21% 15% 36% 22% 5% 1	720
	11th to 20th	Night	23% 14% 36% 21% 5%	703
	21st to end	Night	22% 17% 30% 26% 5%	592
March	1st to 10th	Night	24% 14% 32% 25% 5%	720
	11th to 20th	Night	24% 15% 32% 23% 7%	720
	21st to end	Night	21% 14% 30% 25% 9%	792
April	1st to 10th	Night	26% 14% 28% 26% 6%	720
	11th to 20th	Night	25% 13% 29% 23% 9%	711
	21st to end	Night	24% 15% 27% 25% 9% 1	578
May	1st to 10th	Night	23% 8% 28% 30% 11% 1	360
	11th to 20th	Night	22% 10% 27% 32% 8%	354
	21st to end	Night	15% 5% 33% 34% 12%	389
June	1st to 10th	Night	18% 8% 27% 39% 8%	360
	11th to 20th	Night	16% 6% 27% 36% 14% 1	360
	21st to end	Night	19% 6% 22% 37% 15% 1	360
July	1st to 10th	Night	10% 4 24% 43% 17% 1	350
	11th to 20th	Night	15% 3 21% 42% 19% 1	348
	21st to end	Night	10% 3 22% 46% 18% 1	394
August	1st to 10th	Night	12% 3 20% 37% 27% 1	437
	11th to 20th	Night	12% 3 15% 38% 28% 4	534
	21st to end	Night	14% 6% 23% 35% 20% 2	746
September	1st to 10th	Night	14% 5% 24% 34% 20% 2	720
	11th to 20th	Night	20% 5% 19% 31% 23% 3	720
	21st to end	Night	22% 8% 20% 29% 19% 2	720
October	1st to 10th	Night	24% 8% 25% 27% 14% 2	720
	11th to 20th	Night	29% 9% 29% 22% 10% 1	720
	21st to end	Night	30% 12% 26% 26% 6% 1	792
November	1st to 10th	Night	25% 13% 26% 27% 9% 1	740
	11th to 20th	Night	25% 16% 30% 19% 9% 1	760
	21st to end	Night	34% 13% 24% 23% 6%	760
December	1st to 10th	Night	33% 14% 29% 19% 6%	760
	11th to 20th	Night	29% 15% 27% 23% 5% 1	760
	21st to end	Night	34% 12% 28% 21% 4	836

Page generated at 2024-01-10 19:35:20. Version ac07

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