Morris County Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morris County Observatory clear sky chart from 2005-11-06 to 2024-11-03.

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% 7% 2 6% 4 4 4 4 5% 7% 39%	101335
	Night	17% 7% 2 6% 4 4 4 3 5% 6% 42%	97654
Transparency	Day	44% 6% 12% 22% 15% 2	101090
	Night	43% 6% 12% 22% 15% 2	97519
Seeing	Day	23% 16% 30% 20% 9% 2	14960
	Night	21% 15% 32% 25% 8% 1	24123

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	14% 8% 2 5% 4 4 4 3 5% 5% 46%	2517
	11th to 20th	Day	15% 9% 3 8% 6% 5% 5% 3 5% 6% 34%	2520
	21st to end	Day	21% 10% 5% 7% 4 3 4 3 5% 5% 33%	3064
February	1st to 10th	Day	17% 9% 2 7% 5% 4 4 3 6% 7% 38%	1710
	11th to 20th	Day	15% 7% 3 7% 4 4 4 4 5% 6% 42%	1826
	21st to end	Day	20% 9% 3 5% 5% 4 4 3 5% 5% 37%	1570
March	1st to 10th	Day	26% 8% 2 6% 4 3 4 3 4 5% 36%	3116
	11th to 20th	Day	9% 5% 2 5% 5% 5% 6% 5% 7% 8% 44%	3401
	21st to end	Day	21% 8% 2 5% 4 3 3 2 4 6% 43%	4097
April	1st to 10th	Day	17% 8% 3 6% 4 4 4 3 5% 7% 38%	2280
	11th to 20th	Day	18% 6% 2 6% 4 3 4 4 5% 7% 40%	2254
	21st to end	Day	19% 6% 2 6% 5% 4 4 4 6% 6% 39%	2280
May	1st to 10th	Day	29% 8% 2 6% 4 4 3 3 5% 7% 29%	4128
	11th to 20th	Day	24% 8% 3 8% 5% 4 4 4 5% 6% 29%	4398
	21st to end	Day	13% 5% 2 5% 4 4 4 4 6% 9% 44%	4837
June	1st to 10th	Day	16% 6% 2 5% 4 4 6% 5% 7% 9% 37%	2660
	11th to 20th	Day	16% 6% 2 6% 5% 5% 6% 4 6% 8% 36%	2660
	21st to end	Day	14% 5% 2 6% 5% 4 5% 4 5% 9% 40%	2660
July	1st to 10th	Day	10% 6% 3 7% 6% 6% 6% 4 7% 10% 36%	4440
	11th to 20th	Day	12% 5% 2 6% 4 5% 6% 4 7% 10% 39%	4440
	21st to end	Day	16% 7% 3 8% 6% 6% 5% 5% 6% 7% 32%	4814
August	1st to 10th	Day	23% 5% 2 6% 5% 4 6% 4 7% 7% 33%	4153
	11th to 20th	Day	15% 5% 2 6% 4 4 4 4 5% 8% 44%	3730
	21st to end	Day	13% 5% 2 5% 4 3 4 3 5% 8% 48%	4180
September	1st to 10th	Day	16% 6% 2 5% 4 5% 4 3 5% 7% 44%	2280
	11th to 20th	Day	14% 5% 2 5% 3 4 3 3 5% 8% 49%	2220
	21st to end	Day	20% 6% 3 6% 4 5% 4 3 5% 5% 40%	2090
October	1st to 10th	Day	20% 5% 2 6% 3 4 4 4 5% 6% 41%	1948
	11th to 20th	Day	15% 5% 2 5% 3 4 5% 3 5% 6% 48%	1900
	21st to end	Day	20% 5% 2 4 3 4 4 4 4 6% 44%	1967
November	1st to 10th	Day	14% 6% 3 4 3 3 3 3 4 5% 52%	1689
	11th to 20th	Day	18% 5% 2 4 3 3 3 4 6% 5% 46%	1710
	21st to end	Day	15% 7% 2 5% 4 4 5% 3 5% 7% 43%	1598
December	1st to 10th	Day	19% 9% 2 6% 4 4 4 3 5% 7% 37%	1520
	11th to 20th	Day	21% 6% 2 4 4 3 4 4 5% 6% 42%	1906
	21st to end	Day	18% 9% 3 8% 6% 5% 6% 4 6% 6% 29%	2772
January	1st to 10th	Night	16% 7% 2 4 4 3 3 3 5% 6% 45%	4429
	11th to 20th	Night	16% 9% 3 8% 4 4 4 3 4 6% 41%	4440
	21st to end	Night	24% 11% 2 5% 3 3 4 3 5% 5% 35%	4589
February	1st to 10th	Night	16% 10% 3 6% 4 4 3 3 5% 5% 42%	2470
	11th to 20th	Night	16% 8% 4 6% 4 4 3 4 5% 5% 42%	2238
	21st to end	Night	19% 8% 2 5% 4 4 3 3 4 6% 42%	1884
March	1st to 10th	Night	23% 11% 3 6% 3 3 3 3 4 5% 37%	3724
	11th to 20th	Night	11% 6% 2 5% 5% 4 4 3 5% 6% 49%	3556
	21st to end	Night	18% 10% 3 6% 3 3 3 3 4 4 44%	3535
April	1st to 10th	Night	17% 8% 2 6% 4 5% 5% 4 6% 7% 37%	1900
	11th to 20th	Night	18% 6% 2 5% 4 4 4 4 4 7% 40%	1875
	21st to end	Night	20% 6% 2 5% 3 3 4 3 5% 5% 43%	1900
May	1st to 10th	Night	26% 9% 3 7% 4 4 4 3 5% 7% 29%	2824
	11th to 20th	Night	24% 10% 3 6% 5% 4 3 3 4 5% 32%	2495
	21st to end	Night	15% 6% 2 5% 4 4 4 4 6% 9% 41%	2738
June	1st to 10th	Night	16% 5% 2 5% 4 4 5% 4 5% 7% 44%	1520
	11th to 20th	Night	14% 7% 3 5% 5% 4 4 4 6% 8% 42%	1520
	21st to end	Night	12% 4 2 5% 4 4 5% 3 8% 10% 43%	1520
July	1st to 10th	Night	11% 5% 2 7% 5% 4 5% 4 7% 9% 42%	2520
	11th to 20th	Night	13% 5% 2 6% 4 4 5% 4 7% 10% 38%	2520
	21st to end	Night	17% 7% 2 6% 4 4 5% 4 6% 8% 37%	2739
August	1st to 10th	Night	23% 5% 3 6% 4 4 4 4 6% 8% 33%	2747
	11th to 20th	Night	15% 6% 2 6% 5% 5% 5% 4 5% 7% 40%	3092
	21st to end	Night	11% 5% 2 5% 3 3 4 3 5% 7% 52%	3476
September	1st to 10th	Night	16% 6% 2 6% 5% 4 3 3 4 6% 45%	1900
	11th to 20th	Night	14% 5% 2 5% 3 2 3 3 4 7% 52%	1959
	21st to end	Night	19% 6% 2 5% 3 4 3 2 5% 7% 44%	2090
October	1st to 10th	Night	20% 7% 2 6% 4 3 3 2 5% 6% 42%	2228
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 5% 6% 50%	2280
	21st to end	Night	21% 6% 2 5% 3 3 3 3 4 6% 45%	2631
November	1st to 10th	Night	13% 6% 2 5% 4 3 3 3 5% 6% 52%	2434
	11th to 20th	Night	20% 6% 2 4 3 3 3 3 4 5% 47%	2470
	21st to end	Night	14% 6% 2 5% 4 4 4 4 6% 7% 44%	2579
December	1st to 10th	Night	19% 8% 3 5% 3 4 4 3 6% 7% 38%	2660
	11th to 20th	Night	19% 7% 2 5% 4 3 4 3 6% 7% 41%	3288
	21st to end	Night	19% 10% 3 7% 4 4 4 3 4 5% 37%	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	41% 4 11% 30% 12% 3	2518
	11th to 20th	Day	50% 5% 13% 19% 12% 2	2520
	21st to end	Day	53% 6% 10% 20% 10% 2	3064
February	1st to 10th	Day	46% 6% 13% 21% 12% 2	1710
	11th to 20th	Day	43% 7% 9% 22% 16% 3	1835
	21st to end	Day	49% 5% 10% 21% 12% 3	1570
March	1st to 10th	Day	52% 4 10% 24% 9% 2	3119
	11th to 20th	Day	35% 7% 14% 28% 14% 2	3401
	21st to end	Day	44% 3 9% 15% 23% 5%	4097
April	1st to 10th	Day	46% 5% 10% 19% 15% 5%	2280
	11th to 20th	Day	43% 5% 11% 21% 17% 3	2254
	21st to end	Day	44% 6% 10% 20% 16% 4	2280
May	1st to 10th	Day	54% 6% 12% 15% 11% 1	4142
	11th to 20th	Day	54% 8% 11% 17% 8% 1	4402
	21st to end	Day	35% 8% 13% 25% 18% 2	4837
June	1st to 10th	Day	42% 9% 13% 20% 15% 1	2660
	11th to 20th	Day	44% 8% 12% 23% 11% 2	2660
	21st to end	Day	41% 8% 13% 22% 15% 1	2660
July	1st to 10th	Day	44% 8% 12% 22% 13% 2	4370
	11th to 20th	Day	39% 6% 17% 23% 13% 1	4365
	21st to end	Day	50% 6% 10% 17% 16% 1	4661
August	1st to 10th	Day	49% 7% 14% 20% 10%	4139
	11th to 20th	Day	39% 5% 13% 29% 14% 1	3766
	21st to end	Day	36% 4 9% 29% 20% 2	4180
September	1st to 10th	Day	39% 8% 10% 21% 19% 3	2280
	11th to 20th	Day	34% 6% 10% 23% 25% 3	2220
	21st to end	Day	46% 5% 10% 17% 19% 3	2090
October	1st to 10th	Day	43% 7% 10% 21% 16% 3	1948
	11th to 20th	Day	37% 5% 12% 24% 20% 2	1900
	21st to end	Day	42% 5% 11% 22% 18% 2	1967
November	1st to 10th	Day	35% 5% 12% 24% 21% 3	1689
	11th to 20th	Day	39% 5% 12% 22% 20% 3	1710
	21st to end	Day	41% 4 13% 28% 12% 2	1598
December	1st to 10th	Day	47% 5% 14% 19% 13% 1	1520
	11th to 20th	Day	43% 6% 16% 23% 11% 2	1906
	21st to end	Day	52% 8% 12% 21% 8%	2772
January	1st to 10th	Night	40% 5% 11% 30% 11% 3	4429
	11th to 20th	Night	45% 5% 13% 23% 11% 2	4440
	21st to end	Night	51% 5% 9% 21% 12% 2	4589
February	1st to 10th	Night	44% 6% 12% 24% 12% 2	2470
	11th to 20th	Night	45% 5% 11% 18% 17% 5%	2240
	21st to end	Night	44% 4 8% 24% 16% 3	1884
March	1st to 10th	Night	50% 5% 9% 22% 11% 3	3734
	11th to 20th	Night	35% 6% 14% 25% 17% 2	3557
	21st to end	Night	44% 5% 7% 16% 21% 7%	3535
April	1st to 10th	Night	46% 6% 11% 20% 14% 4	1900
	11th to 20th	Night	44% 6% 10% 19% 20% 2	1875
	21st to end	Night	42% 6% 10% 21% 17% 4	1900
May	1st to 10th	Night	53% 8% 11% 17% 10% 1	2830
	11th to 20th	Night	53% 8% 14% 14% 10% 1	2496
	21st to end	Night	38% 8% 14% 24% 13% 3	2739
June	1st to 10th	Night	40% 5% 12% 22% 19% 1	1520
	11th to 20th	Night	39% 8% 15% 25% 12% 1	1520
	21st to end	Night	34% 10% 16% 25% 15% 1	1520
July	1st to 10th	Night	39% 8% 16% 19% 15% 2	2480
	11th to 20th	Night	40% 7% 15% 25% 13% 1	2472
	21st to end	Night	44% 6% 14% 16% 18% 2	2651
August	1st to 10th	Night	49% 7% 18% 16% 9% 1	2737
	11th to 20th	Night	44% 6% 11% 27% 11% 1	3122
	21st to end	Night	33% 5% 10% 32% 20% 1	3476
September	1st to 10th	Night	40% 6% 11% 23% 19% 1	1900
	11th to 20th	Night	34% 5% 10% 23% 25% 3	1959
	21st to end	Night	42% 5% 8% 22% 22% 1	2090
October	1st to 10th	Night	44% 5% 11% 23% 15% 2	2228
	11th to 20th	Night	36% 6% 13% 27% 17% 2	2280
	21st to end	Night	41% 5% 11% 25% 16% 2	2631
November	1st to 10th	Night	34% 6% 11% 23% 22% 4	2434
	11th to 20th	Night	40% 5% 9% 24% 18% 4	2470
	21st to end	Night	38% 6% 14% 27% 14% 2	2579
December	1st to 10th	Night	45% 7% 12% 23% 12% 1	2660
	11th to 20th	Night	43% 6% 13% 19% 16% 3	3288
	21st to end	Night	49% 6% 12% 22% 11%	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	27% 26% 33% 12% 1 1	180
	11th to 20th	Day	36% 27% 28% 9% 1	180
	21st to end	Day	25% 28% 32% 9% 5%	281
February	1st to 10th	Day	31% 27% 33% 8% 1	270
	11th to 20th	Day	28% 28% 35% 9%	434
	21st to end	Day	32% 24% 28% 12% 3	382
March	1st to 10th	Day	29% 22% 32% 13% 3	460
	11th to 20th	Day	27% 27% 29% 13% 3 1	460
	21st to end	Day	31% 22% 31% 12% 4 1	506
April	1st to 10th	Day	29% 23% 30% 11% 7%	460
	11th to 20th	Day	25% 24% 30% 13% 6% 1	452
	21st to end	Day	30% 19% 34% 13% 3 2	460
May	1st to 10th	Day	33% 19% 29% 14% 5% 1	463
	11th to 20th	Day	23% 16% 35% 18% 7% 1	487
	21st to end	Day	21% 10% 29% 28% 11% 1	529
June	1st to 10th	Day	18% 15% 31% 24% 11% 1	490
	11th to 20th	Day	19% 14% 31% 25% 10% 1	490
	21st to end	Day	17% 12% 33% 26% 11% 1	490
July	1st to 10th	Day	15% 7% 29% 28% 16% 4	485
	11th to 20th	Day	12% 4 28% 36% 17% 2	484
	21st to end	Day	16% 8% 32% 28% 13% 2	532
August	1st to 10th	Day	15% 8% 26% 31% 16% 5%	486
	11th to 20th	Day	15% 7% 27% 32% 14% 5%	479
	21st to end	Day	13% 9% 31% 27% 13% 6%	539
September	1st to 10th	Day	19% 12% 24% 25% 14% 5%	490
	11th to 20th	Day	15% 7% 29% 24% 15% 9%	490
	21st to end	Day	23% 14% 29% 20% 10% 4	490
October	1st to 10th	Day	25% 10% 29% 21% 12% 4	490
	11th to 20th	Day	18% 18% 32% 22% 9% 1	490
	21st to end	Day	24% 17% 31% 19% 8% 1	474
November	1st to 10th	Day	20% 15% 32% 22% 9% 2	371
	11th to 20th	Day	28% 19% 31% 18% 4	370
	21st to end	Day	23% 21% 36% 16% 4	258
December	1st to 10th	Day	28% 27% 28% 11% 6%	180
	11th to 20th	Day	35% 24% 27% 11% 3	180
	21st to end	Day	29% 22% 32% 13% 4 1	198
January	1st to 10th	Night	22% 22% 37% 16% 3	760
	11th to 20th	Night	27% 19% 33% 18% 3	760
	21st to end	Night	21% 22% 38% 17% 2	836
February	1st to 10th	Night	22% 21% 37% 18% 2	760
	11th to 20th	Night	24% 26% 36% 12% 1	743
	21st to end	Night	28% 19% 34% 16% 2	628
March	1st to 10th	Night	24% 23% 32% 18% 4	760
	11th to 20th	Night	23% 24% 33% 17% 3 1	760
	21st to end	Night	22% 21% 37% 15% 5%	836
April	1st to 10th	Night	23% 22% 35% 16% 4	760
	11th to 20th	Night	22% 18% 36% 20% 4	751
	21st to end	Night	23% 16% 34% 23% 4	760
May	1st to 10th	Night	26% 16% 33% 20% 5%	573
	11th to 20th	Night	21% 13% 36% 22% 7%	374
	21st to end	Night	18% 8% 26% 36% 12%	411
June	1st to 10th	Night	19% 7% 29% 33% 11%	380
	11th to 20th	Night	14% 6% 32% 36% 11%	380
	21st to end	Night	12% 5% 28% 45% 9%	380
July	1st to 10th	Night	12% 6% 25% 38% 17% 2	370
	11th to 20th	Night	12% 4 24% 41% 17% 1	368
	21st to end	Night	15% 3 25% 43% 13% 1	416
August	1st to 10th	Night	14% 2 23% 39% 20% 2	515
	11th to 20th	Night	14% 4 22% 36% 22% 1	745
	21st to end	Night	15% 4 24% 38% 18% 1	836
September	1st to 10th	Night	18% 4 28% 33% 16% 2	760
	11th to 20th	Night	16% 5% 23% 32% 19% 3	760
	21st to end	Night	22% 7% 26% 31% 13% 1	760
October	1st to 10th	Night	22% 9% 29% 25% 13% 2	760
	11th to 20th	Night	17% 14% 30% 29% 9%	760
	21st to end	Night	24% 14% 33% 22% 7%	836
November	1st to 10th	Night	17% 14% 34% 26% 9% 1	749
	11th to 20th	Night	24% 15% 31% 23% 6%	760
	21st to end	Night	18% 19% 35% 21% 6% 1	760
December	1st to 10th	Night	25% 18% 32% 20% 4 1	760
	11th to 20th	Night	22% 19% 36% 20% 3	760
	21st to end	Night	23% 19% 36% 19% 2	836

Page generated at 2024-10-31 03:39:25. Version ac07

Copyright © 2024 Attilla Danko.