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 2024-11-12.

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	16% 10% 3 8% 5% 5% 5% 4 5% 7% 32%	101673
	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	97518
Transparency	Day	51% 5% 12% 22% 10% 1	105195
	Night	54% 5% 12% 20% 9% 1	102085
Seeing	Day	23% 14% 29% 21% 11% 3	14411
	Night	23% 11% 27% 27% 11% 1	23533

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	17% 18% 6% 13% 8% 5% 3 3 3 4 21%	2517
	11th to 20th	Day	14% 13% 5% 18% 8% 6% 5% 3 4 4 21%	2520
	21st to end	Day	14% 20% 7% 15% 7% 5% 4 3 4 3 19%	2963
February	1st to 10th	Day	12% 16% 5% 14% 8% 5% 5% 4 4 6% 21%	1710
	11th to 20th	Day	13% 16% 5% 11% 6% 5% 5% 3 5% 6% 27%	1663
	21st to end	Day	18% 14% 4 9% 6% 5% 4 4 5% 6% 25%	1519
March	1st to 10th	Day	20% 15% 5% 8% 5% 4 4 3 4 5% 27%	3208
	11th to 20th	Day	11% 16% 6% 11% 6% 5% 4 3 4 5% 27%	3480
	21st to end	Day	13% 7% 3 6% 6% 4 3 3 5% 6% 44%	3961
April	1st to 10th	Day	22% 12% 3 6% 5% 4 4 3 4 6% 30%	2280
	11th to 20th	Day	23% 9% 2 7% 4 4 3 4 4 5% 35%	2254
	21st to end	Day	22% 10% 3 7% 5% 4 4 3 4 5% 33%	2446
May	1st to 10th	Day	19% 8% 3 7% 5% 4 4 4 6% 7% 32%	4426
	11th to 20th	Day	16% 8% 3 7% 5% 4 4 4 6% 8% 36%	4398
	21st to end	Day	16% 7% 3 7% 5% 4 5% 4 6% 6% 38%	4837
June	1st to 10th	Day	21% 7% 3 8% 5% 4 5% 4 6% 7% 30%	2660
	11th to 20th	Day	15% 6% 2 6% 4 5% 5% 4 5% 8% 39%	2660
	21st to end	Day	17% 7% 3 7% 5% 5% 5% 5% 6% 8% 33%	2660
July	1st to 10th	Day	12% 6% 2 7% 6% 5% 6% 5% 7% 9% 35%	4440
	11th to 20th	Day	12% 6% 3 6% 4 5% 6% 5% 7% 7% 40%	4440
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 45%	4814
August	1st to 10th	Day	12% 6% 3 8% 6% 6% 6% 4 7% 8% 34%	4270
	11th to 20th	Day	16% 6% 2 7% 5% 5% 4 4 7% 8% 36%	4044
	21st to end	Day	11% 5% 2 6% 4 5% 6% 5% 7% 10% 39%	4222
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 3 6% 8% 43%	2280
	11th to 20th	Day	13% 6% 3 6% 4 4 5% 3 5% 7% 45%	2280
	21st to end	Day	18% 6% 3 7% 4 5% 5% 4 6% 7% 35%	2005
October	1st to 10th	Day	20% 9% 2 7% 5% 5% 5% 3 5% 6% 34%	1900
	11th to 20th	Day	25% 12% 3 8% 5% 5% 4 3 4 5% 26%	1900
	21st to end	Day	26% 11% 3 8% 5% 4 5% 3 5% 6% 25%	1977
November	1st to 10th	Day	16% 11% 3 7% 5% 5% 4 4 5% 6% 33%	1693
	11th to 20th	Day	20% 14% 4 10% 6% 5% 5% 3 4 5% 23%	1528
	21st to end	Day	24% 17% 5% 10% 7% 5% 5% 3 4 5% 16%	1520
December	1st to 10th	Day	21% 19% 5% 11% 6% 5% 4 3 4 4 16%	1520
	11th to 20th	Day	20% 17% 4 10% 6% 6% 4 3 4 6% 20%	1906
	21st to end	Day	27% 20% 5% 15% 3 3 2 2 2 3 19%	2772
January	1st to 10th	Night	17% 20% 6% 12% 6% 4 5% 3 3 4 18%	4429
	11th to 20th	Night	14% 13% 5% 14% 8% 6% 6% 4 5% 5% 20%	4440
	21st to end	Night	14% 20% 7% 13% 6% 6% 4 3 4 4 19%	4692
February	1st to 10th	Night	13% 15% 6% 14% 7% 5% 5% 4 5% 5% 21%	2470
	11th to 20th	Night	13% 16% 5% 11% 6% 5% 4 3 5% 5% 26%	2403
	21st to end	Night	15% 15% 4 11% 6% 5% 4 3 4 6% 28%	1934
March	1st to 10th	Night	20% 13% 4 8% 6% 4 4 3 4 4 31%	3628
	11th to 20th	Night	17% 17% 5% 10% 4 4 4 3 6% 6% 24%	3479
	21st to end	Night	13% 9% 4 10% 6% 4 4 3 5% 6% 37%	3670
April	1st to 10th	Night	21% 12% 3 7% 5% 5% 5% 3 4 6% 30%	1900
	11th to 20th	Night	19% 11% 2 7% 4 4 4 4 4 6% 35%	1875
	21st to end	Night	21% 9% 3 9% 5% 4 4 3 5% 5% 32%	1749
May	1st to 10th	Night	21% 11% 3 7% 4 4 4 3 5% 6% 31%	2514
	11th to 20th	Night	18% 8% 3 7% 5% 5% 5% 3 6% 7% 33%	2495
	21st to end	Night	14% 8% 3 8% 5% 4 5% 3 6% 7% 39%	2738
June	1st to 10th	Night	16% 7% 3 8% 5% 4 5% 3 7% 7% 35%	1520
	11th to 20th	Night	14% 6% 3 6% 4 4 4 4 5% 8% 43%	1520
	21st to end	Night	17% 8% 2 6% 6% 5% 5% 3 5% 7% 36%	1520
July	1st to 10th	Night	13% 7% 3 8% 6% 5% 5% 5% 7% 7% 35%	2520
	11th to 20th	Night	14% 7% 2 7% 4 4 5% 4 6% 8% 39%	2520
	21st to end	Night	9% 6% 1 5% 5% 4 5% 3 7% 8% 46%	2739
August	1st to 10th	Night	11% 6% 2 6% 5% 5% 6% 4 8% 8% 39%	2655
	11th to 20th	Night	16% 6% 2 6% 4 5% 4 3 5% 8% 40%	2785
	21st to end	Night	13% 5% 2 6% 5% 4 5% 4 6% 7% 41%	3402
September	1st to 10th	Night	12% 6% 3 6% 5% 4 4 3 5% 8% 45%	1900
	11th to 20th	Night	16% 5% 2 6% 3 3 3 3 5% 7% 47%	1900
	21st to end	Night	19% 7% 3 7% 4 3 3 3 3 6% 42%	2172
October	1st to 10th	Night	20% 8% 2 5% 4 3 4 3 4 6% 39%	2280
	11th to 20th	Night	22% 11% 3 8% 6% 4 4 3 5% 5% 29%	2280
	21st to end	Night	24% 12% 3 9% 4 5% 4 3 5% 5% 26%	2620
November	1st to 10th	Night	19% 12% 3 7% 5% 4 4 4 5% 6% 31%	2602
	11th to 20th	Night	19% 13% 4 9% 6% 5% 4 3 5% 6% 25%	2675
	21st to end	Night	23% 16% 5% 10% 5% 5% 4 3 4 6% 19%	2660
December	1st to 10th	Night	21% 20% 5% 11% 7% 4 4 3 4 5% 16%	2660
	11th to 20th	Night	21% 19% 5% 9% 5% 4 3 3 4 4 23%	3288
	21st to end	Night	28% 20% 5% 12% 4 3 3 2 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	69% 4 11% 9% 6%	2518
	11th to 20th	Day	68% 3 10% 12% 6%	2520
	21st to end	Day	71% 4 8% 10% 6% 1	2963
February	1st to 10th	Day	64% 4 9% 17% 5% 1	1710
	11th to 20th	Day	59% 3 12% 15% 9% 1	1672
	21st to end	Day	60% 4 10% 15% 10% 2	1519
March	1st to 10th	Day	61% 3 9% 16% 10% 1	3211
	11th to 20th	Day	60% 4 11% 15% 9% 1	3480
	21st to end	Day	42% 3 9% 25% 18% 3	3961
April	1st to 10th	Day	55% 4 7% 20% 12% 3	2280
	11th to 20th	Day	52% 4 6% 21% 15% 2	2254
	21st to end	Day	55% 3 7% 16% 15% 4	2446
May	1st to 10th	Day	49% 7% 8% 22% 11% 2	4440
	11th to 20th	Day	45% 6% 13% 24% 11% 1	4402
	21st to end	Day	46% 5% 11% 19% 16% 2	4837
June	1st to 10th	Day	53% 5% 10% 20% 12% 1	2660
	11th to 20th	Day	42% 5% 12% 24% 14% 2	2660
	21st to end	Day	48% 7% 12% 21% 12% 1	2660
July	1st to 10th	Day	43% 6% 14% 26% 10% 1	4370
	11th to 20th	Day	38% 7% 15% 31% 9%	4365
	21st to end	Day	35% 5% 14% 35% 10%	4661
August	1st to 10th	Day	46% 6% 14% 24% 9%	4256
	11th to 20th	Day	44% 6% 17% 26% 7%	4083
	21st to end	Day	37% 6% 16% 29% 11% 1	4222
September	1st to 10th	Day	40% 6% 14% 29% 11%	2280
	11th to 20th	Day	40% 5% 12% 32% 11% 1	2280
	21st to end	Day	48% 5% 14% 24% 9%	2005
October	1st to 10th	Day	52% 4 10% 27% 6%	3160
	11th to 20th	Day	53% 5% 12% 24% 6%	3140
	21st to end	Day	55% 4 19% 18% 4 1	3241
November	1st to 10th	Day	51% 5% 15% 22% 6% 1	1693
	11th to 20th	Day	61% 5% 14% 13% 7% 1	1528
	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	70% 4 14% 9% 3	4429
	11th to 20th	Night	64% 4 14% 13% 4	4440
	21st to end	Night	69% 4 9% 11% 6%	4692
February	1st to 10th	Night	65% 4 10% 15% 6% 1	2470
	11th to 20th	Night	61% 4 9% 19% 7% 1	2405
	21st to end	Night	58% 3 9% 19% 9% 1	1934
March	1st to 10th	Night	57% 4 12% 17% 9% 2	3638
	11th to 20th	Night	60% 5% 11% 15% 8% 1	3480
	21st to end	Night	47% 5% 8% 21% 16% 4	3670
April	1st to 10th	Night	56% 3 8% 18% 12% 2	1900
	11th to 20th	Night	50% 4 7% 22% 14% 2	1875
	21st to end	Night	55% 3 7% 17% 16% 2	1749
May	1st to 10th	Night	52% 6% 8% 21% 10% 3	2520
	11th to 20th	Night	47% 8% 11% 21% 11% 2	2496
	21st to end	Night	44% 5% 12% 21% 16% 2	2739
June	1st to 10th	Night	47% 6% 12% 24% 9% 1	1520
	11th to 20th	Night	39% 6% 11% 27% 15% 2	1520
	21st to end	Night	48% 5% 12% 21% 13% 1	1520
July	1st to 10th	Night	46% 6% 15% 19% 13% 1	2480
	11th to 20th	Night	41% 6% 12% 31% 9%	2472
	21st to end	Night	34% 7% 13% 33% 13%	2651
August	1st to 10th	Night	40% 7% 13% 27% 13%	2645
	11th to 20th	Night	42% 6% 17% 28% 8%	2812
	21st to end	Night	40% 6% 15% 26% 12% 2	3402
September	1st to 10th	Night	40% 5% 11% 30% 14% 1	1900
	11th to 20th	Night	37% 4 16% 33% 10% 1	1900
	21st to end	Night	45% 4 13% 28% 10%	2172
October	1st to 10th	Night	41% 4 13% 30% 12%	3800
	11th to 20th	Night	51% 4 15% 22% 8%	3779
	21st to end	Night	54% 5% 17% 17% 7%	4306
November	1st to 10th	Night	53% 5% 14% 20% 8%	2602
	11th to 20th	Night	60% 5% 13% 14% 8% 1	2675
	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	28% 18% 32% 18% 3 1	180
	21st to end	Day	23% 18% 31% 20% 7% 1	252
February	1st to 10th	Day	28% 20% 35% 13% 4	270
	11th to 20th	Day	24% 26% 37% 10% 1	270
	21st to end	Day	32% 18% 34% 15% 1	331
March	1st to 10th	Day	26% 17% 34% 18% 4 1	460
	11th to 20th	Day	24% 19% 33% 18% 5% 1	460
	21st to end	Day	28% 19% 29% 17% 6% 1	506
April	1st to 10th	Day	32% 18% 27% 15% 8%	460
	11th to 20th	Day	34% 16% 21% 15% 10% 4	452
	21st to end	Day	30% 17% 29% 16% 7% 2	460
May	1st to 10th	Day	27% 13% 27% 22% 8% 3	463
	11th to 20th	Day	20% 17% 30% 20% 10% 5%	487
	21st to end	Day	19% 15% 30% 21% 11% 2	529
June	1st to 10th	Day	25% 10% 29% 24% 11% 1	490
	11th to 20th	Day	17% 13% 27% 25% 14% 4	490
	21st to end	Day	19% 13% 29% 22% 14% 3	490
July	1st to 10th	Day	12% 7% 26% 36% 16% 3	485
	11th to 20th	Day	13% 8% 31% 29% 15% 4	484
	21st to end	Day	13% 7% 30% 31% 15% 5%	532
August	1st to 10th	Day	14% 8% 24% 29% 17% 7%	486
	11th to 20th	Day	15% 6% 23% 27% 20% 9%	479
	21st to end	Day	13% 10% 26% 26% 17% 7%	539
September	1st to 10th	Day	17% 8% 27% 24% 16% 8%	490
	11th to 20th	Day	15% 8% 21% 21% 20% 14%	490
	21st to end	Day	18% 11% 27% 21% 15% 8%	490
October	1st to 10th	Day	25% 13% 23% 20% 14% 4	490
	11th to 20th	Day	29% 17% 30% 15% 8% 1	490
	21st to end	Day	30% 15% 26% 22% 5% 1	479
November	1st to 10th	Day	27% 16% 32% 17% 7% 1	327
	11th to 20th	Day	26% 22% 34% 11% 5% 2	182
	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%	760
	21st to end	Night	19% 12% 33% 28% 8%	836
February	1st to 10th	Night	20% 14% 36% 24% 5% 1	760
	11th to 20th	Night	23% 14% 36% 22% 5%	743
	21st to end	Night	23% 17% 30% 26% 5%	628
March	1st to 10th	Night	24% 15% 31% 25% 5%	760
	11th to 20th	Night	24% 15% 32% 22% 6%	760
	21st to end	Night	21% 15% 31% 25% 9%	836
April	1st to 10th	Night	26% 14% 28% 25% 7%	760
	11th to 20th	Night	25% 14% 29% 23% 9%	751
	21st to end	Night	24% 15% 27% 25% 9% 1	609
May	1st to 10th	Night	22% 7% 29% 30% 10% 1	380
	11th to 20th	Night	22% 10% 26% 34% 8%	374
	21st to end	Night	16% 6% 33% 33% 12%	411
June	1st to 10th	Night	17% 8% 27% 39% 8%	380
	11th to 20th	Night	16% 7% 27% 37% 13% 1	380
	21st to end	Night	21% 6% 22% 36% 14% 1	380
July	1st to 10th	Night	10% 4 24% 44% 17% 1	370
	11th to 20th	Night	14% 4 20% 42% 19% 1	368
	21st to end	Night	10% 3 22% 46% 18% 1	416
August	1st to 10th	Night	12% 3 19% 38% 26% 1	462
	11th to 20th	Night	13% 4 15% 37% 27% 4	564
	21st to end	Night	14% 6% 22% 36% 21% 2	788
September	1st to 10th	Night	15% 5% 24% 34% 20% 2	760
	11th to 20th	Night	19% 5% 19% 30% 24% 4	760
	21st to end	Night	22% 8% 20% 29% 19% 2	760
October	1st to 10th	Night	24% 8% 25% 27% 15% 2	760
	11th to 20th	Night	29% 9% 29% 22% 11% 1	760
	21st to end	Night	29% 12% 27% 25% 6%	836
November	1st to 10th	Night	25% 14% 25% 27% 8% 1	780
	11th to 20th	Night	25% 16% 30% 19% 9% 1	765
	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 2024-11-08 22:45:40. Version ac07

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