Rummy's Stargazing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rummy's Stargazing Site 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% 7% 3 6% 4 4 4 4 5% 7% 37%	101391
	Night	17% 7% 2 6% 4 4 4 3 5% 7% 40%	97624
Transparency	Day	44% 7% 12% 22% 13% 2	104911
	Night	42% 7% 13% 22% 14% 2	102193
Seeing	Day	24% 18% 29% 19% 8% 2	14887
	Night	22% 17% 29% 23% 8% 1	24086

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	13% 12% 3 5% 4 5% 3 4 4 5% 42%	2517
	11th to 20th	Day	14% 11% 6% 11% 7% 4 4 3 4 6% 30%	2520
	21st to end	Day	19% 12% 4 7% 4 4 4 3 5% 6% 31%	3101
February	1st to 10th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 5% 35%	1710
	11th to 20th	Day	13% 9% 3 7% 5% 5% 5% 4 5% 7% 38%	1782
	21st to end	Day	19% 11% 3 7% 5% 4 5% 4 4 5% 35%	1570
March	1st to 10th	Day	24% 10% 3 6% 4 3 3 3 4 5% 34%	3116
	11th to 20th	Day	9% 8% 3 7% 5% 5% 5% 4 5% 8% 42%	3466
	21st to end	Day	20% 10% 3 5% 3 3 3 3 4 5% 42%	4057
April	1st to 10th	Day	17% 10% 2 6% 5% 5% 4 5% 5% 6% 36%	2280
	11th to 20th	Day	17% 9% 3 6% 4 4 4 3 5% 6% 39%	2254
	21st to end	Day	17% 6% 2 5% 5% 6% 5% 3 6% 6% 38%	2280
May	1st to 10th	Day	26% 8% 2 7% 4 4 4 3 5% 7% 31%	4203
	11th to 20th	Day	24% 8% 3 8% 5% 5% 5% 3 5% 6% 27%	4398
	21st to end	Day	14% 4 2 5% 4 4 5% 4 6% 10% 43%	4837
June	1st to 10th	Day	15% 5% 2 7% 6% 5% 5% 4 6% 8% 36%	2660
	11th to 20th	Day	16% 6% 2 6% 4 6% 5% 5% 6% 9% 35%	2660
	21st to end	Day	14% 5% 2 6% 5% 5% 5% 4 6% 8% 39%	2660
July	1st to 10th	Day	10% 5% 2 7% 5% 5% 6% 5% 7% 9% 38%	4440
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 7% 11% 39%	4440
	21st to end	Day	16% 7% 3 7% 6% 5% 5% 4 6% 7% 35%	4814
August	1st to 10th	Day	22% 5% 3 7% 4 5% 6% 4 7% 6% 31%	4120
	11th to 20th	Day	14% 6% 2 6% 4 5% 5% 4 6% 9% 39%	3769
	21st to end	Day	16% 5% 2 4 3 3 4 3 6% 8% 45%	4180
September	1st to 10th	Day	16% 6% 3 5% 3 4 5% 4 5% 8% 41%	2280
	11th to 20th	Day	14% 4 2 5% 3 3 4 4 5% 6% 50%	2247
	21st to end	Day	20% 7% 3 6% 4 4 4 3 5% 5% 39%	2090
October	1st to 10th	Day	20% 7% 2 6% 4 4 4 4 5% 6% 40%	1900
	11th to 20th	Day	16% 4 2 6% 4 4 5% 3 4 7% 45%	1900
	21st to end	Day	21% 6% 2 6% 4 3 4 4 6% 6% 39%	1991
November	1st to 10th	Day	14% 7% 2 5% 3 3 2 2 4 6% 51%	1698
	11th to 20th	Day	19% 8% 2 4 4 3 3 4 6% 5% 43%	1710
	21st to end	Day	17% 7% 2 6% 5% 5% 4 4 6% 7% 39%	1543
December	1st to 10th	Day	19% 10% 3 6% 4 4 4 4 4 6% 34%	1520
	11th to 20th	Day	21% 9% 3 6% 3 4 5% 3 5% 7% 35%	1906
	21st to end	Day	19% 12% 5% 10% 5% 5% 5% 4 6% 6% 25%	2772
January	1st to 10th	Night	16% 7% 2 6% 4 4 4 4 6% 7% 41%	4429
	11th to 20th	Night	15% 9% 4 10% 5% 5% 4 3 5% 6% 34%	4440
	21st to end	Night	22% 11% 3 6% 4 4 4 3 4 5% 33%	4553
February	1st to 10th	Night	16% 10% 3 5% 4 4 4 4 4 6% 40%	2470
	11th to 20th	Night	14% 8% 3 6% 5% 4 4 5% 5% 6% 39%	2283
	21st to end	Night	18% 8% 3 6% 4 5% 3 3 5% 6% 39%	1884
March	1st to 10th	Night	22% 10% 2 7% 3 3 3 3 5% 5% 35%	3724
	11th to 20th	Night	11% 7% 3 5% 4 4 5% 3 6% 7% 45%	3490
	21st to end	Night	15% 10% 3 7% 4 4 3 3 4 5% 43%	3574
April	1st to 10th	Night	17% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	1900
	11th to 20th	Night	19% 7% 2 5% 3 4 4 4 6% 7% 39%	1875
	21st to end	Night	20% 6% 2 5% 3 3 4 3 6% 7% 41%	1900
May	1st to 10th	Night	28% 8% 3 7% 4 3 4 3 5% 6% 30%	2765
	11th to 20th	Night	25% 11% 3 6% 4 3 4 3 4 5% 32%	2495
	21st to end	Night	15% 6% 2 5% 4 4 5% 3 6% 9% 41%	2738
June	1st to 10th	Night	16% 5% 2 5% 4 3 5% 5% 5% 8% 43%	1520
	11th to 20th	Night	16% 5% 1 5% 3 4 5% 5% 6% 9% 42%	1520
	21st to end	Night	13% 4 1 4 5% 4 4 3 8% 9% 45%	1520
July	1st to 10th	Night	11% 4 2 6% 5% 5% 5% 4 7% 9% 41%	2520
	11th to 20th	Night	13% 5% 2 5% 4 4 5% 5% 7% 11% 40%	2520
	21st to end	Night	18% 6% 2 4 3 5% 5% 4 6% 6% 41%	2739
August	1st to 10th	Night	22% 5% 2 6% 4 4 4 4 5% 9% 35%	2792
	11th to 20th	Night	16% 7% 2 6% 4 5% 4 3 5% 6% 43%	3026
	21st to end	Night	14% 4 2 4 3 2 3 4 5% 7% 52%	3476
September	1st to 10th	Night	16% 6% 2 5% 4 4 3 2 5% 6% 47%	1900
	11th to 20th	Night	12% 6% 2 5% 3 3 3 2 4 7% 53%	1931
	21st to end	Night	19% 6% 2 6% 3 3 4 3 5% 6% 43%	2090
October	1st to 10th	Night	23% 5% 2 5% 3 3 3 3 4 6% 43%	2275
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 48%	2280
	21st to end	Night	22% 7% 2 4 2 3 3 3 5% 7% 42%	2605
November	1st to 10th	Night	14% 5% 1 5% 2 4 4 4 5% 5% 50%	2453
	11th to 20th	Night	19% 7% 2 5% 3 3 3 3 5% 5% 44%	2470
	21st to end	Night	15% 6% 2 5% 4 4 4 4 6% 8% 43%	2635
December	1st to 10th	Night	19% 8% 2 6% 5% 4 5% 4 5% 7% 35%	2660
	11th to 20th	Night	18% 9% 2 5% 3 5% 4 4 6% 6% 37%	3288
	21st to end	Night	21% 10% 4 7% 4 4 4 3 5% 6% 32%	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% 6% 11% 28% 8% 2	2518
	11th to 20th	Day	55% 6% 10% 19% 8% 2	2520
	21st to end	Day	54% 7% 10% 19% 9% 1	3101
February	1st to 10th	Day	50% 7% 13% 18% 11% 1	1710
	11th to 20th	Day	46% 7% 10% 21% 14% 2	1791
	21st to end	Day	50% 6% 10% 21% 10% 3	1570
March	1st to 10th	Day	53% 5% 11% 20% 9% 2	3119
	11th to 20th	Day	37% 8% 15% 27% 11% 1	3466
	21st to end	Day	45% 5% 9% 14% 23% 4	4057
April	1st to 10th	Day	47% 7% 10% 19% 13% 4	2280
	11th to 20th	Day	45% 5% 11% 21% 14% 2	2254
	21st to end	Day	45% 7% 11% 20% 14% 4	2280
May	1st to 10th	Day	53% 6% 12% 17% 10% 2	4217
	11th to 20th	Day	55% 8% 11% 17% 8% 1	4402
	21st to end	Day	35% 8% 13% 26% 15% 2	4837
June	1st to 10th	Day	44% 8% 14% 20% 13% 1	2660
	11th to 20th	Day	44% 8% 14% 21% 10% 2	2660
	21st to end	Day	41% 9% 13% 25% 12%	2660
July	1st to 10th	Day	40% 10% 13% 22% 14% 2	4370
	11th to 20th	Day	37% 9% 18% 23% 13% 1	4365
	21st to end	Day	48% 7% 11% 18% 15% 1	4661
August	1st to 10th	Day	51% 8% 13% 19% 9%	4106
	11th to 20th	Day	40% 7% 14% 28% 11%	3806
	21st to end	Day	36% 6% 12% 31% 14% 1	4180
September	1st to 10th	Day	41% 7% 13% 21% 17% 2	2280
	11th to 20th	Day	34% 7% 11% 22% 24% 2	2247
	21st to end	Day	45% 7% 10% 17% 19% 2	2090
October	1st to 10th	Day	42% 5% 10% 18% 22% 3	3160
	11th to 20th	Day	32% 5% 9% 28% 22% 4	3140
	21st to end	Day	30% 5% 17% 26% 20% 3	3255
November	1st to 10th	Day	36% 5% 13% 25% 18% 3	1698
	11th to 20th	Day	42% 6% 11% 23% 16% 2	1710
	21st to end	Day	44% 7% 15% 24% 9% 1	1543
December	1st to 10th	Day	52% 6% 14% 16% 11% 1	1520
	11th to 20th	Day	49% 6% 15% 22% 8%	1906
	21st to end	Day	59% 8% 10% 16% 7%	2772
January	1st to 10th	Night	42% 7% 13% 26% 9% 3	4429
	11th to 20th	Night	49% 7% 13% 21% 9% 1	4440
	21st to end	Night	52% 8% 10% 20% 10% 1	4553
February	1st to 10th	Night	44% 6% 15% 22% 11% 1	2470
	11th to 20th	Night	44% 7% 11% 20% 15% 3	2285
	21st to end	Night	46% 6% 10% 22% 13% 3	1884
March	1st to 10th	Night	50% 6% 11% 20% 10% 2	3734
	11th to 20th	Night	35% 7% 17% 26% 12% 1	3491
	21st to end	Night	44% 5% 8% 17% 21% 5%	3574
April	1st to 10th	Night	48% 6% 11% 19% 12% 3	1900
	11th to 20th	Night	43% 7% 11% 21% 17% 1	1875
	21st to end	Night	42% 7% 11% 20% 16% 3	1900
May	1st to 10th	Night	54% 7% 10% 20% 8% 1	2771
	11th to 20th	Night	54% 8% 12% 15% 10% 1	2496
	21st to end	Night	38% 9% 16% 22% 13% 2	2739
June	1st to 10th	Night	39% 8% 11% 24% 17% 1	1520
	11th to 20th	Night	37% 8% 18% 24% 11% 1	1520
	21st to end	Night	33% 10% 15% 28% 13% 1	1520
July	1st to 10th	Night	39% 9% 16% 19% 16% 1	2480
	11th to 20th	Night	37% 9% 16% 25% 12% 1	2472
	21st to end	Night	41% 8% 14% 17% 19% 1	2651
August	1st to 10th	Night	46% 9% 17% 20% 8%	2782
	11th to 20th	Night	42% 7% 14% 26% 11%	3055
	21st to end	Night	31% 7% 12% 32% 17% 1	3476
September	1st to 10th	Night	38% 6% 12% 25% 18% 1	1900
	11th to 20th	Night	33% 6% 10% 24% 25% 2	1931
	21st to end	Night	41% 6% 11% 21% 20% 1	2090
October	1st to 10th	Night	41% 5% 11% 23% 19% 1	3795
	11th to 20th	Night	29% 4 10% 28% 24% 4	3779
	21st to end	Night	30% 5% 15% 29% 19% 2	4291
November	1st to 10th	Night	35% 6% 14% 22% 20% 3	2453
	11th to 20th	Night	41% 4 12% 22% 17% 3	2470
	21st to end	Night	38% 7% 16% 26% 11% 1	2635
December	1st to 10th	Night	49% 7% 13% 21% 10% 1	2660
	11th to 20th	Night	47% 5% 15% 19% 12% 1	3288
	21st to end	Night	52% 7% 13% 20% 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	37% 26% 26% 11% 2	180
	11th to 20th	Day	39% 27% 24% 8% 2	180
	21st to end	Day	25% 34% 29% 9% 3 1	292
February	1st to 10th	Day	32% 33% 26% 8% 1	270
	11th to 20th	Day	35% 28% 30% 6% 1	390
	21st to end	Day	37% 24% 28% 9% 2	382
March	1st to 10th	Day	32% 21% 33% 11% 2	460
	11th to 20th	Day	30% 27% 28% 12% 3 1	460
	21st to end	Day	33% 26% 27% 10% 3 1	506
April	1st to 10th	Day	30% 25% 28% 12% 5%	460
	11th to 20th	Day	28% 26% 25% 13% 6% 2	452
	21st to end	Day	27% 22% 34% 11% 4 2	460
May	1st to 10th	Day	32% 22% 27% 11% 8% 1	463
	11th to 20th	Day	24% 18% 32% 18% 7% 1	487
	21st to end	Day	19% 12% 29% 26% 12% 2	529
June	1st to 10th	Day	19% 16% 31% 23% 11% 1	490
	11th to 20th	Day	19% 16% 27% 26% 11% 1	490
	21st to end	Day	14% 16% 33% 26% 9% 2	490
July	1st to 10th	Day	14% 9% 28% 27% 18% 4	485
	11th to 20th	Day	11% 6% 29% 31% 20% 2	484
	21st to end	Day	16% 9% 35% 25% 12% 3	532
August	1st to 10th	Day	14% 7% 29% 28% 15% 6%	486
	11th to 20th	Day	14% 8% 26% 33% 15% 5%	479
	21st to end	Day	14% 11% 29% 26% 12% 7%	539
September	1st to 10th	Day	20% 12% 24% 22% 15% 7%	490
	11th to 20th	Day	12% 10% 29% 23% 16% 10%	490
	21st to end	Day	24% 13% 27% 21% 10% 4	490
October	1st to 10th	Day	28% 12% 22% 22% 12% 4	490
	11th to 20th	Day	20% 19% 31% 21% 7% 2	490
	21st to end	Day	27% 18% 29% 20% 6% 1	486
November	1st to 10th	Day	22% 19% 28% 21% 8% 2	374
	11th to 20th	Day	28% 24% 28% 16% 4 1	370
	21st to end	Day	27% 24% 33% 14% 2	203
December	1st to 10th	Day	29% 32% 25% 10% 4 1	180
	11th to 20th	Day	38% 24% 27% 8% 2	180
	21st to end	Day	31% 24% 32% 10% 3	198
January	1st to 10th	Night	23% 25% 36% 13% 3	760
	11th to 20th	Night	28% 23% 31% 17% 1	760
	21st to end	Night	20% 27% 35% 16% 2	836
February	1st to 10th	Night	25% 23% 36% 15% 1	760
	11th to 20th	Night	26% 30% 35% 9% 1	743
	21st to end	Night	32% 23% 29% 14% 2	628
March	1st to 10th	Night	27% 23% 33% 14% 3	760
	11th to 20th	Night	25% 25% 29% 17% 4	760
	21st to end	Night	23% 26% 33% 14% 4 1	836
April	1st to 10th	Night	24% 24% 33% 18% 3	760
	11th to 20th	Night	23% 21% 30% 21% 5%	751
	21st to end	Night	25% 18% 31% 22% 4	760
May	1st to 10th	Night	27% 14% 29% 24% 6% 1	540
	11th to 20th	Night	20% 12% 36% 25% 6% 1	374
	21st to end	Night	17% 7% 26% 38% 12%	411
June	1st to 10th	Night	17% 8% 25% 36% 14%	380
	11th to 20th	Night	16% 7% 30% 35% 12%	380
	21st to end	Night	14% 7% 26% 43% 11%	380
July	1st to 10th	Night	14% 5% 22% 40% 18% 1	370
	11th to 20th	Night	12% 4 23% 43% 16% 2	368
	21st to end	Night	12% 5% 24% 42% 15% 1	416
August	1st to 10th	Night	14% 2 22% 38% 22% 2	547
	11th to 20th	Night	16% 5% 18% 37% 22% 2	703
	21st to end	Night	18% 5% 21% 33% 21% 1	836
September	1st to 10th	Night	18% 7% 27% 31% 16% 2	760
	11th to 20th	Night	16% 6% 25% 28% 20% 5%	760
	21st to end	Night	22% 8% 25% 29% 15% 2	760
October	1st to 10th	Night	26% 11% 23% 24% 15% 1	760
	11th to 20th	Night	20% 14% 30% 29% 7% 1	760
	21st to end	Night	27% 16% 30% 21% 7%	836
November	1st to 10th	Night	19% 18% 30% 24% 8%	755
	11th to 20th	Night	27% 18% 28% 20% 5% 1	760
	21st to end	Night	21% 22% 32% 20% 5%	760
December	1st to 10th	Night	26% 21% 33% 15% 4	760
	11th to 20th	Night	26% 21% 33% 18% 2	760
	21st to end	Night	27% 22% 33% 16% 2	836

Page generated at 2024-11-01 22:47:40. Version ac07

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