Keene
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Keene 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	17% 8% 3 7% 5% 4 4 4 5% 7% 35%	101298
	Night	18% 9% 3 7% 4 4 4 4 5% 6% 36%	97704
Transparency	Day	46% 6% 12% 21% 13% 2	104823
	Night	46% 6% 12% 22% 13% 2	102268
Seeing	Day	24% 18% 29% 18% 8% 2	14911
	Night	22% 16% 29% 24% 8% 1	23845

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	15% 9% 3 6% 4 5% 4 4 5% 7% 37%	2517
	11th to 20th	Day	17% 9% 5% 9% 5% 5% 4 4 5% 6% 31%	2520
	21st to end	Day	19% 13% 5% 9% 4 5% 4 3 5% 5% 29%	2772
February	1st to 10th	Day	15% 12% 4 7% 5% 5% 6% 5% 6% 6% 29%	1729
	11th to 20th	Day	13% 9% 4 10% 6% 5% 4 4 4 7% 34%	1848
	21st to end	Day	18% 11% 4 8% 5% 5% 3 3 5% 5% 33%	1570
March	1st to 10th	Day	22% 15% 3 9% 5% 4 3 3 4 4 27%	3116
	11th to 20th	Day	14% 12% 4 7% 5% 4 4 3 5% 7% 35%	3270
	21st to end	Day	20% 10% 3 8% 4 4 4 3 4 6% 34%	4132
April	1st to 10th	Day	20% 10% 3 8% 5% 4 3 3 5% 6% 34%	2280
	11th to 20th	Day	17% 8% 2 7% 4 5% 5% 4 5% 6% 37%	2254
	21st to end	Day	20% 10% 4 8% 5% 4 4 4 4 5% 33%	2446
May	1st to 10th	Day	26% 10% 3 8% 5% 4 5% 3 4 5% 28%	4106
	11th to 20th	Day	20% 9% 3 7% 5% 4 4 3 5% 6% 33%	4320
	21st to end	Day	15% 5% 2 5% 4 4 4 3 6% 8% 43%	4837
June	1st to 10th	Day	18% 6% 2 7% 6% 5% 5% 4 6% 8% 32%	2660
	11th to 20th	Day	17% 7% 2 7% 5% 4 4 4 5% 8% 36%	2660
	21st to end	Day	18% 7% 3 6% 6% 5% 5% 4 6% 8% 32%	2660
July	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 5% 7% 10% 36%	4440
	11th to 20th	Day	12% 5% 3 6% 5% 5% 5% 5% 8% 11% 34%	4440
	21st to end	Day	18% 7% 3 7% 5% 5% 4 4 6% 7% 35%	4814
August	1st to 10th	Day	16% 7% 3 7% 5% 5% 5% 4 6% 9% 34%	4278
	11th to 20th	Day	14% 7% 3 8% 4 5% 5% 4 7% 9% 35%	3900
	21st to end	Day	9% 5% 2 7% 5% 4 6% 4 8% 9% 41%	4180
September	1st to 10th	Day	13% 7% 2 5% 4 5% 3 5% 5% 9% 44%	2280
	11th to 20th	Day	15% 6% 2 5% 4 3 3 3 4 6% 49%	2129
	21st to end	Day	17% 6% 2 6% 4 4 3 3 5% 8% 42%	2090
October	1st to 10th	Day	22% 8% 2 6% 4 4 5% 3 4 5% 36%	2081
	11th to 20th	Day	15% 7% 2 7% 4 4 4 4 5% 6% 42%	1833
	21st to end	Day	21% 10% 3 6% 6% 4 4 3 4 7% 33%	1881
November	1st to 10th	Day	14% 8% 2 6% 4 4 3 3 4 7% 45%	1698
	11th to 20th	Day	19% 9% 2 7% 3 3 4 3 4 5% 40%	1710
	21st to end	Day	20% 9% 3 7% 3 4 4 2 5% 7% 36%	1649
December	1st to 10th	Day	19% 11% 4 8% 5% 5% 4 3 5% 5% 31%	1520
	11th to 20th	Day	22% 12% 3 5% 4 4 4 2 4 4 36%	1906
	21st to end	Day	23% 12% 3 8% 5% 4 4 4 4 5% 28%	2772
January	1st to 10th	Night	16% 9% 3 6% 4 5% 4 4 4 6% 39%	4429
	11th to 20th	Night	14% 12% 3 10% 7% 5% 5% 4 5% 6% 29%	4440
	21st to end	Night	21% 13% 4 8% 5% 5% 4 3 5% 5% 26%	4884
February	1st to 10th	Night	15% 9% 3 9% 5% 5% 5% 4 5% 6% 34%	2447
	11th to 20th	Night	11% 11% 4 7% 5% 6% 5% 4 6% 7% 35%	2218
	21st to end	Night	15% 10% 3 8% 5% 4 4 4 5% 6% 35%	1884
March	1st to 10th	Night	24% 12% 2 7% 5% 4 4 3 4 5% 30%	3724
	11th to 20th	Night	12% 12% 3 7% 6% 5% 5% 4 5% 5% 35%	3687
	21st to end	Night	23% 11% 3 7% 3 3 4 3 6% 5% 32%	3484
April	1st to 10th	Night	20% 9% 3 7% 4 4 4 3 6% 6% 35%	1900
	11th to 20th	Night	21% 9% 3 5% 4 3 4 2 5% 6% 38%	1875
	21st to end	Night	21% 8% 4 6% 4 4 4 3 5% 5% 37%	1732
May	1st to 10th	Night	25% 9% 3 7% 5% 4 4 4 6% 6% 28%	2834
	11th to 20th	Night	18% 8% 4 9% 7% 6% 5% 5% 7% 6% 27%	2603
	21st to end	Night	16% 6% 2 5% 4 5% 4 4 5% 8% 40%	2738
June	1st to 10th	Night	19% 8% 2 6% 5% 3 4 5% 4 8% 37%	1520
	11th to 20th	Night	19% 7% 2 5% 5% 5% 4 3 6% 7% 38%	1520
	21st to end	Night	16% 7% 2 6% 4 5% 4 5% 7% 7% 37%	1520
July	1st to 10th	Night	12% 6% 2 7% 5% 5% 6% 5% 7% 8% 38%	2520
	11th to 20th	Night	16% 5% 3 7% 4 4 5% 4 6% 7% 39%	2520
	21st to end	Night	17% 7% 2 6% 4 4 4 4 5% 5% 42%	2739
August	1st to 10th	Night	23% 7% 2 7% 4 4 4 3 5% 6% 35%	2620
	11th to 20th	Night	15% 8% 3 8% 4 4 4 3 6% 7% 38%	2910
	21st to end	Night	8% 5% 1 4 3 3 4 3 6% 8% 55%	3476
September	1st to 10th	Night	13% 6% 2 5% 3 3 3 4 5% 7% 48%	1900
	11th to 20th	Night	14% 5% 1 5% 2 3 4 3 5% 6% 52%	2050
	21st to end	Night	17% 5% 2 6% 4 3 4 3 5% 6% 47%	2090
October	1st to 10th	Night	22% 7% 2 6% 4 3 3 2 4 6% 38%	2095
	11th to 20th	Night	16% 7% 2 6% 4 4 4 4 6% 6% 42%	2346
	21st to end	Night	22% 9% 2 6% 4 3 4 3 5% 6% 34%	2717
November	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 5% 5% 45%	2453
	11th to 20th	Night	17% 8% 3 6% 4 3 3 3 4 6% 41%	2470
	21st to end	Night	15% 10% 3 7% 4 4 4 4 5% 6% 39%	2527
December	1st to 10th	Night	20% 11% 3 6% 5% 4 4 3 5% 6% 32%	2660
	11th to 20th	Night	21% 11% 3 6% 4 4 4 4 4 5% 35%	3288
	21st to end	Night	22% 12% 5% 9% 4 4 3 4 4 6% 27%	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	45% 5% 9% 31% 8% 1	2518
	11th to 20th	Day	51% 6% 12% 21% 8% 1	2520
	21st to end	Day	57% 5% 10% 19% 9% 2	2772
February	1st to 10th	Day	51% 7% 12% 19% 10% 1	1729
	11th to 20th	Day	50% 6% 9% 19% 14% 2	1857
	21st to end	Day	54% 4 9% 19% 12% 2	1570
March	1st to 10th	Day	61% 4 10% 12% 11% 2	3119
	11th to 20th	Day	45% 7% 14% 20% 11% 3	3270
	21st to end	Day	50% 4 6% 17% 19% 4	4132
April	1st to 10th	Day	51% 5% 9% 20% 13% 3	2280
	11th to 20th	Day	46% 6% 11% 19% 16% 2	2254
	21st to end	Day	53% 5% 8% 17% 14% 3	2446
May	1st to 10th	Day	57% 7% 10% 15% 9% 1	4120
	11th to 20th	Day	51% 7% 14% 17% 9% 2	4324
	21st to end	Day	36% 8% 13% 26% 15% 1	4837
June	1st to 10th	Day	48% 7% 12% 21% 11% 1	2660
	11th to 20th	Day	46% 6% 12% 20% 14% 2	2660
	21st to end	Day	49% 8% 12% 19% 11% 1	2660
July	1st to 10th	Day	41% 8% 12% 22% 15% 1	4370
	11th to 20th	Day	40% 8% 16% 24% 11% 1	4365
	21st to end	Day	46% 6% 13% 20% 13% 1	4661
August	1st to 10th	Day	46% 7% 15% 21% 10%	4264
	11th to 20th	Day	44% 7% 15% 27% 7% 1	3939
	21st to end	Day	35% 7% 14% 29% 14% 1	4180
September	1st to 10th	Day	37% 6% 13% 26% 17% 1	2280
	11th to 20th	Day	36% 5% 9% 25% 22% 2	2129
	21st to end	Day	41% 6% 10% 24% 16% 3	2090
October	1st to 10th	Day	48% 5% 7% 23% 15% 2	3458
	11th to 20th	Day	39% 4 11% 26% 17% 3	3023
	21st to end	Day	38% 4 10% 31% 14% 3	3081
November	1st to 10th	Day	40% 5% 14% 24% 14% 2	1698
	11th to 20th	Day	45% 5% 10% 21% 17% 3	1710
	21st to end	Day	47% 6% 15% 21% 10% 1	1649
December	1st to 10th	Day	55% 6% 13% 15% 11% 1	1520
	11th to 20th	Day	51% 5% 11% 17% 14% 1	1906
	21st to end	Day	58% 6% 10% 16% 9% 1	2772
January	1st to 10th	Night	44% 6% 13% 24% 10% 2	4429
	11th to 20th	Night	53% 7% 12% 17% 8% 2	4440
	21st to end	Night	59% 6% 9% 15% 9% 1	4884
February	1st to 10th	Night	49% 6% 14% 20% 10% 2	2447
	11th to 20th	Night	45% 7% 11% 21% 14% 2	2220
	21st to end	Night	47% 6% 11% 23% 10% 4	1884
March	1st to 10th	Night	55% 5% 9% 19% 10% 2	3734
	11th to 20th	Night	46% 8% 12% 20% 11% 2	3688
	21st to end	Night	50% 6% 7% 13% 19% 4	3484
April	1st to 10th	Night	48% 6% 10% 19% 14% 2	1900
	11th to 20th	Night	46% 7% 9% 20% 16% 2	1875
	21st to end	Night	48% 6% 10% 17% 15% 4	1732
May	1st to 10th	Night	54% 7% 11% 18% 8% 1	2840
	11th to 20th	Night	54% 9% 14% 14% 8% 2	2604
	21st to end	Night	40% 7% 15% 22% 13% 2	2739
June	1st to 10th	Night	45% 7% 12% 24% 10% 1	1520
	11th to 20th	Night	44% 7% 14% 21% 12% 1	1520
	21st to end	Night	42% 8% 16% 20% 13% 1	1520
July	1st to 10th	Night	42% 8% 14% 22% 14% 1	2480
	11th to 20th	Night	42% 7% 12% 24% 14%	2472
	21st to end	Night	44% 6% 11% 24% 14% 1	2651
August	1st to 10th	Night	50% 6% 13% 21% 9%	2610
	11th to 20th	Night	45% 6% 17% 23% 9%	2937
	21st to end	Night	27% 5% 17% 35% 15% 1	3476
September	1st to 10th	Night	35% 6% 12% 27% 18% 1	1900
	11th to 20th	Night	33% 5% 11% 27% 21% 2	2050
	21st to end	Night	38% 5% 11% 27% 17% 2	2090
October	1st to 10th	Night	42% 4 16% 24% 13% 1	3498
	11th to 20th	Night	35% 4 12% 25% 21% 3	3895
	21st to end	Night	39% 5% 11% 33% 12% 1	4467
November	1st to 10th	Night	41% 5% 12% 23% 17% 2	2453
	11th to 20th	Night	43% 6% 11% 23% 15% 3	2470
	21st to end	Night	45% 6% 15% 23% 11% 1	2527
December	1st to 10th	Night	51% 6% 12% 21% 9% 1	2660
	11th to 20th	Night	49% 6% 13% 16% 14% 2	3288
	21st to end	Night	58% 5% 10% 19% 8%	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	28% 24% 29% 16% 3	180
	11th to 20th	Day	34% 22% 33% 8% 3 1	180
	21st to end	Day	22% 31% 32% 11% 4	198
February	1st to 10th	Day	32% 30% 26% 10% 1	309
	11th to 20th	Day	32% 26% 29% 12% 2	456
	21st to end	Day	33% 25% 28% 13% 2	382
March	1st to 10th	Day	30% 21% 34% 12% 3	460
	11th to 20th	Day	30% 28% 26% 11% 4 1	460
	21st to end	Day	31% 23% 29% 10% 5% 3	506
April	1st to 10th	Day	35% 22% 25% 11% 6% 2	460
	11th to 20th	Day	30% 26% 25% 11% 6% 2	452
	21st to end	Day	30% 18% 31% 14% 6% 1	460
May	1st to 10th	Day	34% 22% 24% 13% 6% 2	463
	11th to 20th	Day	21% 20% 36% 15% 6% 2	487
	21st to end	Day	20% 14% 32% 25% 7% 2	529
June	1st to 10th	Day	21% 16% 34% 18% 9% 2	490
	11th to 20th	Day	19% 16% 32% 24% 8% 2	490
	21st to end	Day	20% 17% 34% 19% 8% 2	490
July	1st to 10th	Day	17% 12% 29% 28% 12% 2	485
	11th to 20th	Day	15% 9% 32% 30% 11% 2	484
	21st to end	Day	15% 13% 35% 26% 9% 3	532
August	1st to 10th	Day	13% 12% 28% 31% 12% 5%	486
	11th to 20th	Day	15% 11% 28% 27% 15% 5%	479
	21st to end	Day	13% 12% 29% 28% 12% 6%	539
September	1st to 10th	Day	19% 12% 25% 25% 14% 6%	490
	11th to 20th	Day	17% 15% 25% 20% 14% 10%	490
	21st to end	Day	19% 13% 33% 18% 11% 6%	490
October	1st to 10th	Day	29% 15% 21% 21% 11% 4	490
	11th to 20th	Day	23% 17% 28% 21% 9% 2	454
	21st to end	Day	34% 13% 27% 21% 4 2	429
November	1st to 10th	Day	23% 19% 26% 20% 11% 1	374
	11th to 20th	Day	31% 21% 26% 18% 3 1	370
	21st to end	Day	32% 17% 29% 17% 4 1	309
December	1st to 10th	Day	27% 28% 29% 12% 3 1	180
	11th to 20th	Day	39% 24% 26% 10% 1	180
	21st to end	Day	33% 23% 30% 10% 5%	198
January	1st to 10th	Night	20% 24% 35% 18% 3	760
	11th to 20th	Night	27% 22% 31% 18% 2	760
	21st to end	Night	20% 23% 33% 21% 3	836
February	1st to 10th	Night	23% 23% 34% 19% 2	760
	11th to 20th	Night	23% 24% 35% 16% 1	743
	21st to end	Night	28% 24% 29% 18% 2	628
March	1st to 10th	Night	25% 21% 33% 19% 3	760
	11th to 20th	Night	23% 26% 29% 18% 4	760
	21st to end	Night	26% 20% 30% 18% 6%	836
April	1st to 10th	Night	27% 18% 30% 21% 4	760
	11th to 20th	Night	25% 20% 27% 21% 6%	751
	21st to end	Night	27% 18% 29% 21% 5%	592
May	1st to 10th	Night	29% 12% 31% 22% 5%	570
	11th to 20th	Night	20% 17% 33% 25% 5%	443
	21st to end	Night	19% 8% 27% 35% 10% 1	411
June	1st to 10th	Night	20% 9% 27% 33% 10% 1	380
	11th to 20th	Night	20% 10% 29% 31% 9% 1	380
	21st to end	Night	18% 8% 27% 38% 8% 1	380
July	1st to 10th	Night	14% 5% 29% 40% 12% 1	370
	11th to 20th	Night	14% 4 27% 37% 16% 2	368
	21st to end	Night	13% 5% 29% 38% 14% 1	416
August	1st to 10th	Night	14% 6% 24% 36% 18% 1	440
	11th to 20th	Night	16% 7% 26% 32% 18% 2	638
	21st to end	Night	15% 7% 23% 35% 19% 2	836
September	1st to 10th	Night	16% 7% 28% 30% 17% 2	760
	11th to 20th	Night	16% 8% 24% 29% 19% 4	760
	21st to end	Night	18% 9% 27% 29% 15% 1	760
October	1st to 10th	Night	26% 12% 21% 27% 12% 2	760
	11th to 20th	Night	20% 14% 30% 25% 10% 1	760
	21st to end	Night	28% 17% 27% 22% 6% 1	836
November	1st to 10th	Night	20% 18% 29% 25% 8%	755
	11th to 20th	Night	22% 24% 26% 21% 6% 1	760
	21st to end	Night	23% 20% 32% 18% 6% 1	760
December	1st to 10th	Night	27% 21% 30% 18% 4	760
	11th to 20th	Night	26% 21% 33% 17% 4	760
	21st to end	Night	27% 22% 33% 15% 3	836

Page generated at 2024-11-01 22:47:42. Version ac07

Copyright © 2024 Attilla Danko.