Tooley Pond
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tooley Pond clear sky chart from 2005-11-06 to 2025-01-22.

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	18% 13% 4 9% 5% 4 4 3 5% 6% 27%	105280
	Night	18% 15% 5% 11% 5% 4 4 3 4 5% 26%	104103
Transparency	Day	57% 6% 10% 18% 8% 1	108750
	Night	61% 5% 10% 16% 8% 1	108722
Seeing	Day	27% 18% 29% 16% 7% 2	14787
	Night	27% 18% 29% 19% 7% 1	23984

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% 23% 8% 20% 9% 5% 4 3 3 2 10%	2597
	11th to 20th	Day	11% 21% 8% 21% 13% 4 4 2 2 3 11%	2600
	21st to end	Day	15% 23% 10% 14% 6% 6% 6% 3 4 3 10%	2883
February	1st to 10th	Day	14% 20% 8% 16% 8% 5% 3 2 3 4 16%	1710
	11th to 20th	Day	13% 19% 8% 15% 9% 5% 4 2 4 4 18%	1731
	21st to end	Day	16% 21% 6% 14% 7% 5% 3 2 4 3 18%	1570
March	1st to 10th	Day	21% 16% 6% 10% 6% 4 3 2 4 5% 23%	3116
	11th to 20th	Day	12% 25% 8% 11% 5% 4 4 2 3 4 23%	3406
	21st to end	Day	15% 13% 6% 11% 6% 3 3 2 3 5% 32%	4088
April	1st to 10th	Day	20% 18% 5% 7% 3 3 3 2 4 4 29%	2280
	11th to 20th	Day	20% 15% 3 7% 4 4 4 3 3 4 32%	2254
	21st to end	Day	23% 15% 3 7% 5% 4 3 3 4 5% 29%	2346
May	1st to 10th	Day	24% 12% 4 6% 5% 4 4 4 5% 6% 26%	4416
	11th to 20th	Day	18% 10% 3 8% 6% 5% 5% 4 5% 6% 29%	4398
	21st to end	Day	17% 8% 2 6% 4 5% 5% 4 6% 8% 35%	4837
June	1st to 10th	Day	25% 8% 2 6% 5% 5% 5% 4 6% 6% 27%	2660
	11th to 20th	Day	21% 7% 2 7% 4 5% 5% 4 6% 7% 32%	2660
	21st to end	Day	23% 7% 3 7% 5% 5% 4 5% 5% 6% 30%	2660
July	1st to 10th	Day	15% 7% 2 6% 5% 5% 5% 5% 7% 9% 35%	4440
	11th to 20th	Day	15% 8% 2 7% 4 5% 5% 5% 8% 10% 32%	4440
	21st to end	Day	13% 8% 3 7% 5% 5% 6% 4 7% 7% 36%	4814
August	1st to 10th	Day	18% 9% 3 7% 4 4 5% 4 5% 8% 32%	4374
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 6% 7% 32%	3885
	21st to end	Day	20% 7% 2 5% 4 4 4 3 6% 9% 36%	4180
September	1st to 10th	Day	17% 7% 2 6% 5% 4 4 3 6% 7% 38%	2280
	11th to 20th	Day	18% 7% 2 5% 3 3 4 3 6% 6% 42%	2243
	21st to end	Day	21% 7% 2 6% 4 4 5% 4 6% 7% 34%	2087
October	1st to 10th	Day	25% 10% 3 8% 4 4 4 3 4 5% 29%	1900
	11th to 20th	Day	22% 13% 3 8% 5% 4 4 3 4 5% 27%	1900
	21st to end	Day	26% 18% 4 7% 4 3 4 3 4 5% 22%	1915
November	1st to 10th	Day	15% 20% 3 8% 5% 5% 5% 3 5% 5% 26%	1761
	11th to 20th	Day	16% 17% 5% 11% 6% 5% 5% 3 3 4 26%	1703
	21st to end	Day	18% 24% 6% 13% 6% 4 4 3 3 4 16%	1600
December	1st to 10th	Day	17% 25% 9% 18% 9% 4 3 2 3 3 7%	2600
	11th to 20th	Day	17% 20% 9% 17% 6% 3 3 2 3 3 15%	2986
	21st to end	Day	18% 20% 6% 13% 6% 4 3 4 3 4 19%	3960
January	1st to 10th	Night	14% 25% 8% 20% 7% 4 3 2 2 3 13%	4569
	11th to 20th	Night	10% 19% 10% 22% 12% 5% 4 2 3 3 9%	4580
	21st to end	Night	17% 22% 8% 17% 6% 6% 4 2 2 3 13%	4794
February	1st to 10th	Night	15% 21% 7% 17% 8% 4 4 3 3 3 15%	2470
	11th to 20th	Night	12% 17% 9% 15% 9% 6% 5% 3 4 4 18%	2334
	21st to end	Night	14% 18% 6% 14% 8% 5% 4 3 4 5% 19%	1884
March	1st to 10th	Night	20% 13% 4 10% 7% 4 3 3 4 5% 28%	3724
	11th to 20th	Night	15% 21% 8% 11% 5% 3 3 2 4 4 23%	3550
	21st to end	Night	16% 17% 5% 10% 6% 3 3 2 3 4 32%	3544
April	1st to 10th	Night	20% 18% 4 9% 4 4 3 3 3 5% 29%	1900
	11th to 20th	Night	19% 16% 4 7% 5% 4 4 3 3 5% 30%	1875
	21st to end	Night	24% 11% 4 7% 4 3 3 3 4 5% 31%	1834
May	1st to 10th	Night	26% 12% 3 7% 5% 5% 4 4 4 5% 24%	2553
	11th to 20th	Night	19% 12% 3 8% 4 4 4 3 4 6% 31%	2495
	21st to end	Night	18% 8% 2 7% 4 4 4 3 6% 6% 38%	2738
June	1st to 10th	Night	22% 7% 2 6% 5% 4 5% 5% 6% 7% 31%	1520
	11th to 20th	Night	21% 7% 2 6% 3 4 4 4 6% 7% 37%	1520
	21st to end	Night	21% 9% 3 7% 4 5% 4 3 5% 6% 33%	1520
July	1st to 10th	Night	15% 7% 3 6% 6% 5% 5% 4 5% 7% 37%	2520
	11th to 20th	Night	16% 7% 3 6% 4 4 4 4 5% 8% 40%	2520
	21st to end	Night	13% 8% 2 6% 4 4 5% 4 6% 7% 40%	2739
August	1st to 10th	Night	20% 9% 3 7% 4 3 3 3 5% 6% 37%	2551
	11th to 20th	Night	18% 9% 3 8% 4 4 4 3 5% 6% 35%	2910
	21st to end	Night	13% 8% 3 6% 4 5% 5% 4 6% 8% 40%	3476
September	1st to 10th	Night	16% 8% 3 6% 3 4 4 4 5% 6% 42%	1900
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 5% 6% 47%	1935
	21st to end	Night	19% 7% 2 5% 3 4 3 4 6% 7% 39%	2090
October	1st to 10th	Night	25% 10% 3 5% 4 4 4 4 5% 6% 30%	2280
	11th to 20th	Night	21% 12% 3 7% 5% 3 4 3 5% 6% 30%	2280
	21st to end	Night	27% 18% 3 8% 4 4 4 3 4 4 21%	2682
November	1st to 10th	Night	18% 16% 4 7% 4 5% 4 3 5% 5% 28%	2537
	11th to 20th	Night	18% 18% 5% 10% 5% 4 3 3 4 5% 25%	2695
	21st to end	Night	19% 22% 6% 12% 5% 4 3 3 5% 4 18%	2800
December	1st to 10th	Night	17% 25% 11% 21% 5% 3 3 2 2 3 8%	4580
	11th to 20th	Night	18% 22% 8% 14% 5% 4 3 2 3 3 17%	5208
	21st to end	Night	20% 20% 6% 14% 5% 5% 4 3 3 4 17%	6996

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	79% 6% 5% 8% 2	2598
	11th to 20th	Day	82% 3 4 6% 3 1	2600
	21st to end	Day	78% 5% 7% 6% 3 1	2883
February	1st to 10th	Day	74% 4 5% 13% 3 1	1710
	11th to 20th	Day	71% 5% 6% 10% 7% 1	1740
	21st to end	Day	71% 5% 7% 10% 7% 1	1570
March	1st to 10th	Day	64% 6% 8% 12% 9% 1	3119
	11th to 20th	Day	65% 7% 10% 10% 6% 1	3406
	21st to end	Day	54% 5% 7% 17% 14% 2	4088
April	1st to 10th	Day	59% 5% 7% 17% 11% 2	2280
	11th to 20th	Day	55% 5% 6% 19% 13% 2	2254
	21st to end	Day	58% 5% 9% 15% 11% 3	2346
May	1st to 10th	Day	56% 7% 10% 19% 7% 1	4430
	11th to 20th	Day	52% 10% 11% 19% 7% 1	4402
	21st to end	Day	44% 9% 11% 24% 10% 1	4837
June	1st to 10th	Day	56% 7% 11% 16% 11%	2660
	11th to 20th	Day	50% 7% 11% 22% 9% 1	2660
	21st to end	Day	54% 8% 11% 18% 9% 1	2660
July	1st to 10th	Day	45% 4 14% 28% 10%	4370
	11th to 20th	Day	46% 5% 15% 29% 5%	4365
	21st to end	Day	46% 7% 12% 28% 8%	4661
August	1st to 10th	Day	50% 5% 14% 21% 9%	4360
	11th to 20th	Day	50% 6% 15% 22% 6%	3924
	21st to end	Day	46% 5% 15% 25% 9%	4180
September	1st to 10th	Day	44% 7% 14% 25% 10% 1	2280
	11th to 20th	Day	41% 6% 12% 26% 14% 1	2243
	21st to end	Day	48% 7% 13% 22% 9% 1	2087
October	1st to 10th	Day	52% 3 10% 25% 10%	3160
	11th to 20th	Day	52% 4 13% 18% 12% 1	3140
	21st to end	Day	53% 3 15% 23% 5% 1	3127
November	1st to 10th	Day	59% 8% 11% 15% 7%	1761
	11th to 20th	Day	62% 6% 10% 12% 7% 4	1703
	21st to end	Day	72% 5% 10% 8% 4	1600
December	1st to 10th	Day	84% 3 6% 5% 1	2600
	11th to 20th	Day	76% 4 5% 10% 4	2986
	21st to end	Day	71% 4 5% 9% 10% 1	3960
January	1st to 10th	Night	79% 5% 6% 8% 3	4569
	11th to 20th	Night	81% 6% 4 5% 2 1	4580
	21st to end	Night	79% 4 5% 8% 4 1	4794
February	1st to 10th	Night	75% 5% 7% 8% 5%	2470
	11th to 20th	Night	69% 6% 7% 12% 6%	2336
	21st to end	Night	67% 6% 8% 13% 6% 1	1884
March	1st to 10th	Night	58% 7% 9% 16% 9% 1	3734
	11th to 20th	Night	62% 6% 12% 13% 6% 1	3551
	21st to end	Night	56% 5% 6% 18% 13% 2	3544
April	1st to 10th	Night	60% 4 8% 18% 9% 1	1900
	11th to 20th	Night	57% 6% 8% 17% 12% 1	1875
	21st to end	Night	55% 5% 9% 16% 12% 2	1834
May	1st to 10th	Night	58% 9% 9% 13% 9% 1	2559
	11th to 20th	Night	52% 8% 11% 19% 8% 1	2496
	21st to end	Night	44% 8% 12% 20% 15% 1	2739
June	1st to 10th	Night	50% 9% 14% 18% 8% 1	1520
	11th to 20th	Night	46% 6% 14% 19% 14% 1	1520
	21st to end	Night	50% 7% 13% 20% 9%	1520
July	1st to 10th	Night	47% 4 13% 22% 13% 1	2480
	11th to 20th	Night	43% 4 16% 30% 6%	2472
	21st to end	Night	43% 6% 13% 28% 8% 1	2651
August	1st to 10th	Night	49% 5% 15% 23% 8%	2541
	11th to 20th	Night	50% 6% 16% 21% 7%	2937
	21st to end	Night	43% 5% 14% 29% 9% 1	3476
September	1st to 10th	Night	43% 7% 13% 26% 11% 1	1900
	11th to 20th	Night	37% 6% 14% 30% 13%	1935
	21st to end	Night	43% 7% 12% 25% 11% 1	2090
October	1st to 10th	Night	53% 4 10% 23% 9% 1	3800
	11th to 20th	Night	50% 4 13% 20% 11% 2	3779
	21st to end	Night	57% 4 14% 19% 5% 1	4420
November	1st to 10th	Night	58% 7% 12% 14% 8% 2	2537
	11th to 20th	Night	61% 7% 9% 13% 7% 3	2695
	21st to end	Night	70% 6% 8% 11% 4	2800
December	1st to 10th	Night	85% 3 6% 5% 1	4580
	11th to 20th	Night	74% 4 5% 10% 6%	5208
	21st to end	Night	73% 4 5% 8% 7% 2	6996

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% 30% 33% 11% 4 1	200
	11th to 20th	Day	30% 29% 33% 7% 2 1	200
	21st to end	Day	26% 26% 33% 13% 1	231
February	1st to 10th	Day	38% 33% 25% 4	270
	11th to 20th	Day	32% 32% 31% 4	338
	21st to end	Day	36% 24% 31% 7% 1	382
March	1st to 10th	Day	28% 27% 30% 13% 3	460
	11th to 20th	Day	32% 25% 30% 9% 2 1	460
	21st to end	Day	35% 26% 24% 11% 4 1	506
April	1st to 10th	Day	36% 23% 25% 11% 5%	460
	11th to 20th	Day	38% 20% 21% 13% 6% 2	452
	21st to end	Day	36% 18% 30% 9% 6% 2	460
May	1st to 10th	Day	33% 17% 29% 13% 6% 2	463
	11th to 20th	Day	24% 16% 32% 20% 7% 1	487
	21st to end	Day	22% 16% 32% 21% 9% 1	529
June	1st to 10th	Day	30% 15% 32% 17% 5% 1	490
	11th to 20th	Day	23% 14% 29% 25% 6% 3	490
	21st to end	Day	25% 18% 32% 17% 7% 1	490
July	1st to 10th	Day	18% 10% 33% 25% 12% 2	485
	11th to 20th	Day	19% 14% 29% 29% 8% 2	484
	21st to end	Day	17% 12% 37% 26% 7% 2	532
August	1st to 10th	Day	18% 11% 29% 26% 12% 3	486
	11th to 20th	Day	19% 10% 29% 26% 11% 5%	479
	21st to end	Day	22% 12% 31% 21% 11% 4	539
September	1st to 10th	Day	21% 12% 29% 19% 12% 6%	490
	11th to 20th	Day	17% 11% 25% 18% 18% 10%	490
	21st to end	Day	21% 13% 29% 20% 14% 4	490
October	1st to 10th	Day	30% 15% 25% 14% 12% 3	490
	11th to 20th	Day	28% 23% 27% 14% 7% 1	490
	21st to end	Day	39% 16% 27% 15% 2	446
November	1st to 10th	Day	30% 22% 28% 13% 6% 1	395
	11th to 20th	Day	33% 22% 27% 12% 3 2	303
	21st to end	Day	35% 23% 33% 9% 1	200
December	1st to 10th	Day	41% 16% 32% 10% 2	200
	11th to 20th	Day	34% 30% 29% 6% 2	200
	21st to end	Day	34% 22% 32% 9% 2 1	220
January	1st to 10th	Night	28% 27% 33% 10% 2	800
	11th to 20th	Night	30% 26% 28% 13% 3	800
	21st to end	Night	21% 25% 34% 16% 4	841
February	1st to 10th	Night	28% 28% 31% 13% 1	760
	11th to 20th	Night	25% 28% 33% 12% 2	743
	21st to end	Night	28% 24% 32% 13% 2	628
March	1st to 10th	Night	27% 22% 33% 16% 2	760
	11th to 20th	Night	30% 23% 29% 15% 3 1	760
	21st to end	Night	28% 21% 29% 17% 4 1	836
April	1st to 10th	Night	29% 22% 29% 17% 2	760
	11th to 20th	Night	32% 20% 26% 16% 6%	751
	21st to end	Night	32% 17% 28% 17% 6%	694
May	1st to 10th	Night	29% 14% 30% 21% 6% 1	406
	11th to 20th	Night	20% 14% 34% 26% 7%	374
	21st to end	Night	17% 13% 32% 29% 8% 1	411
June	1st to 10th	Night	25% 9% 29% 27% 10%	380
	11th to 20th	Night	23% 7% 30% 28% 12%	380
	21st to end	Night	22% 11% 33% 26% 8%	380
July	1st to 10th	Night	11% 6% 32% 38% 12%	370
	11th to 20th	Night	13% 5% 29% 36% 14% 2	368
	21st to end	Night	15% 8% 31% 36% 9% 1	416
August	1st to 10th	Night	20% 6% 25% 35% 13% 1	397
	11th to 20th	Night	21% 6% 21% 30% 19% 2	637
	21st to end	Night	18% 6% 31% 32% 13% 1	836
September	1st to 10th	Night	20% 9% 30% 25% 14% 1	760
	11th to 20th	Night	19% 7% 24% 28% 19% 4	760
	21st to end	Night	23% 11% 27% 23% 16% 1	760
October	1st to 10th	Night	29% 13% 26% 18% 12% 1	760
	11th to 20th	Night	29% 16% 26% 21% 6% 1	760
	21st to end	Night	37% 17% 27% 17% 2	836
November	1st to 10th	Night	30% 19% 28% 17% 6%	780
	11th to 20th	Night	30% 22% 28% 13% 7% 1	800
	21st to end	Night	34% 23% 25% 13% 4	800
December	1st to 10th	Night	35% 25% 26% 13% 2	800
	11th to 20th	Night	31% 25% 30% 11% 3 1	800
	21st to end	Night	32% 26% 28% 10% 4	880

Page generated at 2025-01-19 03:06:48. Version ac07

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