Norton Cemetery
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Norton Cemetery clear sky chart from 2005-11-06 to 2024-12-24.

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	13% 10% 4 9% 6% 5% 5% 4 6% 7% 29%	101861
	Night	13% 11% 4 10% 6% 5% 5% 4 6% 7% 30%	98278
Transparency	Day	52% 4 11% 21% 11% 1	105347
	Night	52% 4 11% 21% 11% 1	102881
Seeing	Day	23% 23% 30% 16% 6% 2	14801
	Night	21% 22% 29% 20% 8% 1	23873

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	8% 13% 8% 11% 7% 5% 5% 5% 5% 8% 25%	2517
	11th to 20th	Day	8% 15% 7% 16% 12% 6% 4 4 4 5% 20%	2520
	21st to end	Day	10% 14% 6% 13% 7% 6% 6% 5% 7% 6% 20%	2776
February	1st to 10th	Day	10% 13% 6% 12% 8% 7% 6% 4 7% 6% 22%	1710
	11th to 20th	Day	6% 9% 6% 13% 9% 7% 6% 6% 6% 7% 25%	1786
	21st to end	Day	10% 15% 4 10% 8% 5% 5% 4 6% 6% 26%	1570
March	1st to 10th	Day	17% 15% 5% 12% 7% 5% 4 4 5% 5% 23%	3116
	11th to 20th	Day	8% 17% 6% 10% 7% 7% 6% 4 5% 6% 24%	3285
	21st to end	Day	12% 12% 4 9% 7% 5% 4 4 5% 5% 35%	4161
April	1st to 10th	Day	15% 14% 4 8% 6% 5% 5% 4 5% 6% 28%	2280
	11th to 20th	Day	15% 12% 4 9% 5% 5% 5% 3 5% 5% 33%	2254
	21st to end	Day	19% 14% 4 8% 5% 5% 4 3 5% 6% 28%	2403
May	1st to 10th	Day	19% 13% 4 9% 5% 5% 4 4 5% 6% 27%	4288
	11th to 20th	Day	17% 10% 3 8% 6% 6% 5% 4 6% 8% 27%	4398
	21st to end	Day	14% 6% 2 7% 6% 5% 5% 4 6% 9% 36%	4837
June	1st to 10th	Day	21% 8% 3 8% 5% 5% 5% 4 7% 7% 26%	2660
	11th to 20th	Day	15% 8% 3 8% 6% 5% 5% 5% 7% 7% 32%	2660
	21st to end	Day	19% 9% 3 8% 6% 5% 6% 5% 7% 6% 27%	2660
July	1st to 10th	Day	12% 6% 2 7% 6% 6% 6% 5% 8% 8% 33%	4440
	11th to 20th	Day	10% 6% 2 7% 7% 5% 7% 6% 9% 10% 32%	4440
	21st to end	Day	12% 6% 2 8% 6% 6% 7% 5% 7% 8% 34%	4814
August	1st to 10th	Day	14% 7% 2 8% 6% 6% 6% 5% 8% 8% 30%	4423
	11th to 20th	Day	12% 8% 4 10% 6% 6% 6% 7% 7% 8% 27%	3864
	21st to end	Day	13% 5% 3 7% 5% 6% 6% 5% 6% 9% 36%	4180
September	1st to 10th	Day	13% 7% 2 6% 5% 4 5% 4 7% 8% 40%	2280
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 4 5% 8% 44%	2198
	21st to end	Day	12% 8% 3 6% 5% 5% 5% 4 7% 9% 36%	2090
October	1st to 10th	Day	18% 11% 3 8% 5% 5% 4 4 5% 6% 31%	1971
	11th to 20th	Day	14% 12% 4 8% 5% 5% 5% 4 6% 6% 32%	1881
	21st to end	Day	18% 12% 4 11% 6% 4 4 3 5% 6% 28%	1881
November	1st to 10th	Day	10% 11% 5% 10% 6% 5% 6% 4 6% 6% 30%	1761
	11th to 20th	Day	11% 12% 4 10% 6% 7% 5% 4 6% 6% 29%	1775
	21st to end	Day	12% 14% 5% 11% 6% 6% 5% 5% 6% 7% 25%	1600
December	1st to 10th	Day	12% 18% 8% 14% 7% 6% 5% 5% 4 5% 17%	1600
	11th to 20th	Day	13% 13% 4 13% 6% 5% 4 5% 6% 6% 24%	1986
	21st to end	Day	17% 15% 6% 10% 6% 5% 4 4 6% 6% 23%	2796
January	1st to 10th	Night	11% 14% 6% 14% 6% 6% 5% 4 6% 6% 23%	4429
	11th to 20th	Night	6% 14% 7% 17% 12% 7% 6% 5% 5% 6% 16%	4440
	21st to end	Night	13% 11% 6% 14% 8% 6% 6% 4 5% 5% 20%	4879
February	1st to 10th	Night	7% 11% 5% 12% 10% 7% 6% 6% 6% 8% 21%	2470
	11th to 20th	Night	7% 9% 6% 11% 10% 6% 7% 5% 7% 8% 25%	2279
	21st to end	Night	8% 13% 4 11% 9% 5% 5% 5% 6% 7% 27%	1884
March	1st to 10th	Night	16% 13% 4 9% 6% 6% 5% 4 6% 5% 26%	3724
	11th to 20th	Night	10% 14% 6% 11% 6% 5% 5% 3 5% 7% 29%	3671
	21st to end	Night	11% 12% 6% 11% 6% 4 4 3 5% 4 34%	3471
April	1st to 10th	Night	13% 11% 5% 9% 6% 6% 6% 4 6% 6% 29%	1900
	11th to 20th	Night	16% 11% 4 8% 6% 5% 5% 4 6% 7% 29%	1875
	21st to end	Night	17% 10% 4 8% 6% 4 5% 4 4 6% 33%	1777
May	1st to 10th	Night	18% 15% 4 8% 5% 4 4 4 6% 7% 24%	2679
	11th to 20th	Night	17% 11% 3 7% 5% 4 4 4 4 6% 34%	2495
	21st to end	Night	13% 7% 2 7% 4 5% 5% 4 7% 9% 38%	2738
June	1st to 10th	Night	18% 8% 2 5% 5% 4 5% 4 7% 8% 34%	1520
	11th to 20th	Night	15% 7% 2 6% 4 4 4 5% 6% 8% 39%	1520
	21st to end	Night	17% 6% 3 6% 5% 5% 4 4 7% 8% 35%	1520
July	1st to 10th	Night	11% 6% 3 8% 6% 5% 6% 4 6% 8% 37%	2520
	11th to 20th	Night	11% 5% 2 6% 5% 5% 5% 4 7% 8% 42%	2520
	21st to end	Night	10% 6% 2 7% 5% 5% 5% 5% 6% 8% 42%	2739
August	1st to 10th	Night	13% 7% 3 7% 5% 5% 4 4 5% 7% 38%	2506
	11th to 20th	Night	12% 7% 3 8% 4 5% 6% 5% 6% 7% 37%	2929
	21st to end	Night	9% 6% 2 5% 5% 5% 5% 4 6% 9% 44%	3476
September	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 7% 6% 45%	1900
	11th to 20th	Night	11% 7% 2 5% 4 4 4 3 4 7% 48%	1981
	21st to end	Night	15% 7% 2 6% 5% 4 4 4 6% 8% 40%	2090
October	1st to 10th	Night	16% 10% 3 8% 5% 5% 5% 3 5% 7% 32%	2208
	11th to 20th	Night	15% 11% 3 6% 5% 5% 5% 4 6% 6% 34%	2298
	21st to end	Night	18% 12% 4 9% 5% 6% 5% 4 5% 6% 25%	2717
November	1st to 10th	Night	12% 12% 4 9% 6% 6% 5% 5% 6% 7% 29%	2537
	11th to 20th	Night	13% 10% 5% 11% 5% 5% 5% 5% 6% 6% 30%	2625
	21st to end	Night	11% 13% 5% 10% 7% 5% 4 5% 7% 7% 25%	2800
December	1st to 10th	Night	12% 14% 7% 14% 8% 5% 5% 4 5% 7% 17%	2800
	11th to 20th	Night	13% 13% 5% 13% 6% 5% 5% 4 6% 6% 23%	3428
	21st to end	Night	17% 13% 5% 16% 5% 5% 4 4 6% 6% 21%	4933

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	59% 2 7% 23% 7% 2	2518
	11th to 20th	Day	69% 2 6% 15% 6% 2	2520
	21st to end	Day	64% 2 10% 15% 8% 2	2776
February	1st to 10th	Day	61% 3 8% 18% 8% 3	1710
	11th to 20th	Day	56% 4 8% 18% 13% 2	1795
	21st to end	Day	57% 2 10% 15% 13% 3	1570
March	1st to 10th	Day	67% 2 7% 11% 10% 2	3119
	11th to 20th	Day	61% 2 8% 15% 11% 3	3285
	21st to end	Day	54% 1 5% 14% 22% 3	4161
April	1st to 10th	Day	55% 3 9% 17% 14% 3	2280
	11th to 20th	Day	54% 4 7% 20% 14% 1	2254
	21st to end	Day	59% 2 9% 15% 12% 3	2403
May	1st to 10th	Day	60% 2 7% 21% 10% 1	4302
	11th to 20th	Day	56% 2 13% 19% 8% 1	4402
	21st to end	Day	47% 3 11% 27% 11% 1	4837
June	1st to 10th	Day	56% 4 12% 18% 10% 1	2660
	11th to 20th	Day	48% 4 11% 24% 11% 2	2660
	21st to end	Day	55% 4 11% 19% 9% 1	2660
July	1st to 10th	Day	43% 6% 15% 25% 10%	4370
	11th to 20th	Day	40% 7% 16% 30% 6%	4365
	21st to end	Day	46% 6% 11% 29% 8%	4661
August	1st to 10th	Day	48% 5% 14% 21% 10% 1	4409
	11th to 20th	Day	49% 7% 16% 23% 5%	3904
	21st to end	Day	42% 6% 17% 24% 10% 1	4180
September	1st to 10th	Day	41% 4 10% 31% 13% 1	2280
	11th to 20th	Day	40% 3 10% 29% 17% 1	2198
	21st to end	Day	46% 3 13% 24% 12% 2	2090
October	1st to 10th	Day	45% 7% 10% 25% 14%	3270
	11th to 20th	Day	44% 4 12% 22% 15% 3	3109
	21st to end	Day	43% 4 13% 31% 8% 1	3081
November	1st to 10th	Day	53% 4 11% 18% 12% 1	1761
	11th to 20th	Day	54% 4 9% 14% 16% 3	1775
	21st to end	Day	56% 4 12% 18% 9% 1	1600
December	1st to 10th	Day	69% 3 8% 14% 6% 1	1600
	11th to 20th	Day	60% 3 10% 16% 10% 1	1986
	21st to end	Day	64% 2 7% 16% 12%	2796
January	1st to 10th	Night	62% 3 7% 19% 9%	4429
	11th to 20th	Night	69% 2 8% 12% 7% 2	4440
	21st to end	Night	64% 3 7% 15% 10% 2	4879
February	1st to 10th	Night	59% 4 9% 15% 10% 2	2470
	11th to 20th	Night	55% 5% 8% 18% 14% 1	2281
	21st to end	Night	56% 3 9% 18% 11% 2	1884
March	1st to 10th	Night	60% 2 7% 16% 12% 2	3734
	11th to 20th	Night	57% 1 10% 19% 11% 2	3672
	21st to end	Night	54% 2 4 18% 18% 4	3471
April	1st to 10th	Night	54% 3 8% 18% 15% 2	1900
	11th to 20th	Night	54% 2 11% 20% 12% 1	1875
	21st to end	Night	53% 2 9% 19% 13% 3	1777
May	1st to 10th	Night	61% 2 7% 20% 9% 1	2685
	11th to 20th	Night	53% 2 11% 24% 9% 1	2496
	21st to end	Night	44% 3 15% 22% 15% 1	2739
June	1st to 10th	Night	48% 4 13% 24% 10% 1	1520
	11th to 20th	Night	42% 4 15% 25% 13% 1	1520
	21st to end	Night	46% 4 15% 26% 9%	1520
July	1st to 10th	Night	43% 6% 16% 24% 12% 1	2480
	11th to 20th	Night	36% 6% 17% 31% 9%	2472
	21st to end	Night	38% 8% 16% 28% 9% 1	2651
August	1st to 10th	Night	43% 6% 18% 24% 9%	2496
	11th to 20th	Night	42% 5% 19% 25% 8%	2955
	21st to end	Night	33% 7% 18% 31% 11% 1	3476
September	1st to 10th	Night	36% 5% 15% 30% 12% 1	1900
	11th to 20th	Night	37% 3 13% 31% 15% 1	1981
	21st to end	Night	42% 4 12% 26% 13% 2	2090
October	1st to 10th	Night	48% 7% 10% 24% 11% 1	3689
	11th to 20th	Night	41% 6% 12% 25% 10% 6%	3809
	21st to end	Night	48% 5% 15% 24% 8% 1	4467
November	1st to 10th	Night	54% 4 10% 18% 12% 2	2537
	11th to 20th	Night	54% 4 7% 19% 12% 4	2625
	21st to end	Night	55% 4 13% 19% 9% 1	2800
December	1st to 10th	Night	65% 4 10% 15% 7%	2800
	11th to 20th	Night	60% 4 8% 15% 12% 1	3428
	21st to end	Night	65% 2 7% 15% 10%	4933

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	16% 30% 31% 17% 6%	180
	11th to 20th	Day	23% 31% 36% 7% 2 1	180
	21st to end	Day	21% 29% 37% 11% 3 1	200
February	1st to 10th	Day	31% 42% 22% 3 1	270
	11th to 20th	Day	29% 31% 31% 7% 1	394
	21st to end	Day	32% 25% 30% 11% 2	382
March	1st to 10th	Day	27% 28% 30% 12% 2	460
	11th to 20th	Day	28% 30% 28% 10% 3 1	460
	21st to end	Day	33% 28% 22% 11% 5% 1	506
April	1st to 10th	Day	34% 23% 28% 12% 3 1	460
	11th to 20th	Day	34% 26% 22% 12% 3 3	452
	21st to end	Day	33% 26% 25% 10% 5% 1	460
May	1st to 10th	Day	30% 27% 26% 10% 5% 3	463
	11th to 20th	Day	21% 23% 32% 19% 3 1	487
	21st to end	Day	22% 22% 31% 19% 4 2	529
June	1st to 10th	Day	28% 19% 32% 15% 5% 1	490
	11th to 20th	Day	18% 20% 34% 19% 7% 1	490
	21st to end	Day	24% 23% 29% 17% 6% 1	490
July	1st to 10th	Day	17% 13% 36% 23% 9% 2	485
	11th to 20th	Day	12% 16% 41% 23% 7% 1	484
	21st to end	Day	15% 14% 40% 23% 6% 2	532
August	1st to 10th	Day	14% 16% 33% 24% 10% 3	486
	11th to 20th	Day	13% 15% 34% 22% 11% 4	479
	21st to end	Day	13% 17% 33% 22% 10% 5%	539
September	1st to 10th	Day	17% 16% 31% 19% 11% 7%	490
	11th to 20th	Day	13% 17% 26% 21% 14% 9%	490
	21st to end	Day	14% 20% 32% 18% 10% 5%	490
October	1st to 10th	Day	25% 21% 25% 16% 10% 2	490
	11th to 20th	Day	24% 26% 24% 18% 7% 1	480
	21st to end	Day	30% 21% 31% 16% 2	429
November	1st to 10th	Day	28% 21% 28% 16% 7%	395
	11th to 20th	Day	29% 30% 22% 14% 4 1	375
	21st to end	Day	31% 33% 24% 11% 2	200
December	1st to 10th	Day	24% 33% 27% 14% 4	200
	11th to 20th	Day	32% 34% 26% 9%	200
	21st to end	Day	28% 30% 32% 7% 2	204
January	1st to 10th	Night	20% 28% 34% 15% 3	760
	11th to 20th	Night	24% 24% 35% 13% 3	760
	21st to end	Night	12% 31% 35% 18% 3	836
February	1st to 10th	Night	19% 31% 34% 14% 2	760
	11th to 20th	Night	21% 30% 32% 15% 2	743
	21st to end	Night	21% 30% 29% 17% 3	628
March	1st to 10th	Night	26% 23% 31% 17% 3	760
	11th to 20th	Night	25% 29% 28% 13% 5% 1	760
	21st to end	Night	24% 26% 28% 17% 4 1	836
April	1st to 10th	Night	25% 24% 30% 17% 3	760
	11th to 20th	Night	26% 26% 25% 18% 6% 1	751
	21st to end	Night	26% 22% 27% 20% 5%	637
May	1st to 10th	Night	26% 18% 28% 21% 6%	480
	11th to 20th	Night	21% 20% 29% 24% 6% 1	374
	21st to end	Night	15% 17% 35% 21% 11%	411
June	1st to 10th	Night	21% 13% 32% 23% 11%	380
	11th to 20th	Night	19% 12% 26% 32% 11% 1	380
	21st to end	Night	18% 13% 29% 30% 9% 1	380
July	1st to 10th	Night	12% 11% 30% 32% 15% 1	370
	11th to 20th	Night	12% 7% 30% 33% 16% 2	368
	21st to end	Night	12% 9% 30% 37% 12% 1	416
August	1st to 10th	Night	11% 9% 27% 35% 16% 1	378
	11th to 20th	Night	11% 9% 28% 33% 16% 3	642
	21st to end	Night	13% 10% 28% 29% 18% 1	836
September	1st to 10th	Night	14% 14% 25% 30% 14% 3	760
	11th to 20th	Night	15% 13% 23% 25% 21% 4	760
	21st to end	Night	17% 14% 26% 23% 18% 2	760
October	1st to 10th	Night	22% 17% 25% 21% 14% 1	760
	11th to 20th	Night	24% 20% 24% 22% 9% 1	760
	21st to end	Night	27% 24% 26% 18% 5%	836
November	1st to 10th	Night	24% 24% 28% 18% 6% 1	780
	11th to 20th	Night	24% 27% 27% 14% 7% 2	800
	21st to end	Night	23% 29% 26% 16% 5% 1	800
December	1st to 10th	Night	23% 31% 29% 15% 3	800
	11th to 20th	Night	26% 25% 29% 17% 4 1	800
	21st to end	Night	25% 29% 32% 13% 2	851

Page generated at 2024-12-21 04:13:50. Version ac07

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