Avonmore
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Avonmore clear sky chart from 2005-11-06 to 2024-10-25.

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% 10% 3 8% 5% 4 4 4 5% 7% 32%	101478
	Night	18% 12% 4 8% 5% 4 4 3 5% 6% 31%	97334
Transparency	Day	51% 7% 12% 21% 9% 1	101236
	Night	54% 7% 11% 18% 9% 1	97196
Seeing	Day	23% 15% 29% 21% 9% 3	14509
	Night	23% 12% 29% 26% 9% 1	23524

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	18% 18% 4 13% 6% 4 4 4 4 4 21%	2517
	11th to 20th	Day	14% 15% 7% 11% 7% 6% 5% 4 5% 5% 21%	2520
	21st to end	Day	15% 20% 7% 10% 6% 6% 5% 4 5% 6% 16%	2832
February	1st to 10th	Day	16% 17% 4 10% 6% 4 5% 3 5% 6% 23%	1710
	11th to 20th	Day	15% 14% 5% 12% 7% 4 4 3 5% 5% 27%	1710
	21st to end	Day	19% 15% 5% 8% 6% 4 4 4 5% 5% 25%	1570
March	1st to 10th	Day	20% 13% 4 10% 6% 4 4 3 4 5% 27%	3116
	11th to 20th	Day	14% 17% 4 10% 6% 5% 5% 3 4 5% 26%	3404
	21st to end	Day	15% 8% 3 9% 5% 4 4 3 5% 6% 39%	4088
April	1st to 10th	Day	22% 13% 3 7% 4 3 3 3 4 5% 32%	2280
	11th to 20th	Day	22% 10% 3 8% 5% 3 3 2 4 5% 35%	2254
	21st to end	Day	23% 10% 3 8% 4 4 4 3 5% 5% 31%	2389
May	1st to 10th	Day	21% 9% 3 7% 5% 4 5% 4 6% 7% 30%	4426
	11th to 20th	Day	18% 11% 3 8% 5% 4 4 3 5% 7% 32%	4398
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 4 6% 8% 37%	4837
June	1st to 10th	Day	23% 8% 3 7% 5% 5% 4 4 6% 6% 29%	2660
	11th to 20th	Day	15% 6% 3 6% 5% 5% 5% 5% 6% 8% 37%	2660
	21st to end	Day	20% 8% 2 7% 4 5% 4 4 7% 9% 30%	2660
July	1st to 10th	Day	12% 6% 3 7% 5% 5% 6% 5% 7% 9% 35%	4440
	11th to 20th	Day	13% 7% 3 6% 4 5% 6% 4 7% 9% 37%	4440
	21st to end	Day	12% 5% 2 6% 4 4 5% 4 7% 8% 43%	4814
August	1st to 10th	Day	15% 8% 3 7% 5% 5% 5% 4 6% 9% 34%	4423
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 6% 7% 39%	3929
	21st to end	Day	16% 6% 2 6% 5% 4 5% 4 6% 8% 38%	4180
September	1st to 10th	Day	14% 6% 3 6% 4 4 4 3 7% 7% 43%	2280
	11th to 20th	Day	13% 5% 1 5% 4 4 4 3 5% 7% 48%	2247
	21st to end	Day	18% 6% 2 6% 4 4 3 4 4 8% 40%	2080
October	1st to 10th	Day	20% 7% 2 7% 5% 4 4 4 4 8% 34%	1900
	11th to 20th	Day	19% 11% 3 9% 5% 5% 4 3 5% 5% 30%	1900
	21st to end	Day	26% 12% 3 7% 4 4 4 3 4 5% 27%	1845
November	1st to 10th	Day	16% 10% 4 8% 5% 5% 5% 4 5% 6% 32%	1671
	11th to 20th	Day	18% 14% 3 8% 5% 4 4 4 4 7% 29%	1580
	21st to end	Day	20% 14% 5% 10% 5% 5% 5% 3 5% 6% 21%	1520
December	1st to 10th	Day	23% 17% 6% 10% 6% 5% 4 4 4 6% 16%	1520
	11th to 20th	Day	22% 16% 5% 9% 5% 5% 4 3 5% 5% 22%	1906
	21st to end	Day	26% 18% 5% 10% 5% 4 4 2 3 3 20%	2772
January	1st to 10th	Night	18% 17% 6% 12% 6% 5% 4 3 4 5% 20%	4429
	11th to 20th	Night	13% 17% 6% 14% 7% 6% 6% 4 5% 5% 18%	4440
	21st to end	Night	18% 19% 7% 12% 5% 5% 3 2 4 4 20%	4820
February	1st to 10th	Night	16% 15% 5% 13% 6% 6% 5% 3 5% 5% 22%	2470
	11th to 20th	Night	14% 15% 4 13% 5% 5% 4 3 5% 5% 27%	2355
	21st to end	Night	16% 17% 5% 8% 6% 4 4 3 4 4 29%	1884
March	1st to 10th	Night	20% 12% 4 8% 5% 4 5% 3 3 4 32%	3724
	11th to 20th	Night	18% 17% 4 10% 5% 4 3 3 4 5% 27%	3553
	21st to end	Night	15% 12% 3 7% 5% 3 3 3 4 5% 39%	3544
April	1st to 10th	Night	23% 10% 3 7% 5% 4 4 3 5% 6% 31%	1900
	11th to 20th	Night	20% 10% 3 6% 5% 4 4 4 4 5% 34%	1875
	21st to end	Night	22% 9% 3 7% 4 3 3 3 4 6% 34%	1804
May	1st to 10th	Night	20% 9% 4 7% 4 5% 5% 4 7% 8% 27%	2514
	11th to 20th	Night	21% 10% 3 6% 4 4 3 3 5% 6% 35%	2495
	21st to end	Night	14% 7% 3 6% 4 4 5% 4 6% 8% 38%	2738
June	1st to 10th	Night	18% 8% 2 7% 6% 5% 5% 4 7% 10% 29%	1520
	11th to 20th	Night	15% 8% 2 5% 4 4 4 3 6% 9% 39%	1520
	21st to end	Night	20% 7% 2 6% 5% 4 3 4 7% 8% 34%	1520
July	1st to 10th	Night	13% 8% 3 8% 5% 5% 4 4 7% 8% 34%	2520
	11th to 20th	Night	13% 7% 2 6% 4 4 4 4 6% 9% 41%	2520
	21st to end	Night	12% 7% 2 6% 5% 4 5% 4 7% 9% 40%	2739
August	1st to 10th	Night	15% 8% 3 7% 4 4 5% 3 6% 8% 38%	2506
	11th to 20th	Night	15% 8% 2 6% 4 4 4 3 5% 8% 39%	2865
	21st to end	Night	13% 6% 3 6% 4 5% 5% 4 6% 8% 40%	3476
September	1st to 10th	Night	11% 7% 2 7% 5% 5% 4 4 5% 6% 44%	1900
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 5% 7% 49%	1932
	21st to end	Night	16% 6% 2 6% 4 4 5% 3 5% 6% 42%	2098
October	1st to 10th	Night	19% 9% 2 6% 4 4 5% 4 5% 6% 37%	2280
	11th to 20th	Night	20% 9% 3 8% 4 5% 4 3 5% 6% 33%	2280
	21st to end	Night	23% 10% 3 8% 5% 4 4 3 5% 6% 28%	2616
November	1st to 10th	Night	20% 10% 4 8% 4 4 4 3 5% 6% 33%	2407
	11th to 20th	Night	18% 12% 3 8% 5% 5% 5% 4 4 6% 32%	2598
	21st to end	Night	22% 13% 5% 10% 6% 4 4 3 4 5% 24%	2660
December	1st to 10th	Night	21% 17% 6% 10% 6% 4 5% 4 5% 5% 17%	2660
	11th to 20th	Night	23% 16% 4 9% 5% 4 4 3 3 4 25%	3288
	21st to end	Night	30% 17% 4 11% 4 3 4 2 3 3 18%	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	65% 7% 14% 9% 5%	2518
	11th to 20th	Day	62% 8% 12% 11% 6% 1	2520
	21st to end	Day	68% 8% 11% 9% 4 1	2832
February	1st to 10th	Day	63% 4 8% 19% 3 1	1710
	11th to 20th	Day	59% 5% 11% 16% 8% 1	1719
	21st to end	Day	61% 5% 11% 13% 9% 1	1570
March	1st to 10th	Day	59% 5% 10% 19% 7% 1	3119
	11th to 20th	Day	58% 8% 11% 14% 8% 1	3404
	21st to end	Day	44% 7% 8% 21% 18% 3	4088
April	1st to 10th	Day	55% 4 6% 20% 12% 3	2280
	11th to 20th	Day	52% 4 7% 20% 15% 2	2254
	21st to end	Day	54% 5% 8% 15% 13% 3	2389
May	1st to 10th	Day	50% 9% 9% 20% 10% 2	4440
	11th to 20th	Day	50% 8% 12% 19% 9% 1	4402
	21st to end	Day	43% 8% 11% 24% 13% 1	4837
June	1st to 10th	Day	53% 7% 11% 18% 11% 1	2660
	11th to 20th	Day	42% 7% 12% 24% 12% 2	2660
	21st to end	Day	50% 8% 12% 20% 10% 1	2660
July	1st to 10th	Day	43% 7% 13% 26% 11%	4370
	11th to 20th	Day	40% 7% 15% 30% 7%	4365
	21st to end	Day	37% 8% 14% 32% 10%	4661
August	1st to 10th	Day	47% 7% 15% 23% 9%	4409
	11th to 20th	Day	41% 6% 18% 28% 7%	3968
	21st to end	Day	42% 7% 16% 24% 11%	4180
September	1st to 10th	Day	39% 7% 13% 27% 13%	2280
	11th to 20th	Day	36% 6% 12% 32% 13%	2247
	21st to end	Day	43% 7% 14% 26% 10%	2080
October	1st to 10th	Day	49% 5% 12% 23% 11%	1900
	11th to 20th	Day	55% 7% 14% 17% 6%	1900
	21st to end	Day	59% 5% 11% 16% 7% 1	1845
November	1st to 10th	Day	51% 7% 13% 21% 7% 1	1671
	11th to 20th	Day	56% 6% 11% 17% 9% 1	1580
	21st to end	Day	64% 8% 12% 12% 5%	1520
December	1st to 10th	Day	70% 6% 12% 10% 2	1520
	11th to 20th	Day	64% 7% 11% 14% 3	1906
	21st to end	Day	71% 4 8% 14% 4	2772
January	1st to 10th	Night	66% 7% 14% 10% 4	4429
	11th to 20th	Night	64% 11% 12% 9% 4	4440
	21st to end	Night	68% 6% 11% 10% 5% 1	4820
February	1st to 10th	Night	65% 5% 9% 15% 6% 1	2470
	11th to 20th	Night	58% 5% 9% 19% 7%	2357
	21st to end	Night	59% 5% 8% 17% 11% 1	1884
March	1st to 10th	Night	55% 5% 9% 20% 9% 2	3734
	11th to 20th	Night	59% 7% 12% 14% 7% 2	3554
	21st to end	Night	48% 4 5% 24% 16% 3	3544
April	1st to 10th	Night	55% 5% 8% 19% 13% 2	1900
	11th to 20th	Night	51% 6% 8% 19% 14% 2	1875
	21st to end	Night	51% 5% 8% 17% 15% 4	1804
May	1st to 10th	Night	51% 10% 11% 16% 9% 3	2520
	11th to 20th	Night	48% 9% 10% 19% 13% 2	2496
	21st to end	Night	40% 7% 14% 20% 17% 2	2739
June	1st to 10th	Night	48% 8% 13% 18% 11% 1	1520
	11th to 20th	Night	41% 6% 13% 21% 17% 1	1520
	21st to end	Night	46% 8% 13% 20% 12% 1	1520
July	1st to 10th	Night	45% 7% 13% 21% 14% 1	2480
	11th to 20th	Night	39% 7% 15% 31% 8%	2472
	21st to end	Night	40% 9% 15% 22% 14%	2651
August	1st to 10th	Night	45% 6% 15% 25% 9%	2496
	11th to 20th	Night	43% 6% 15% 28% 7%	2892
	21st to end	Night	40% 7% 15% 24% 12% 1	3476
September	1st to 10th	Night	41% 7% 10% 27% 15% 1	1900
	11th to 20th	Night	34% 6% 13% 33% 13% 1	1932
	21st to end	Night	41% 7% 11% 27% 13% 1	2098
October	1st to 10th	Night	47% 6% 11% 23% 11% 1	2280
	11th to 20th	Night	51% 6% 12% 22% 9%	2280
	21st to end	Night	57% 6% 14% 15% 8% 1	2616
November	1st to 10th	Night	51% 5% 14% 20% 9% 1	2407
	11th to 20th	Night	53% 6% 12% 19% 9% 2	2598
	21st to end	Night	62% 6% 12% 15% 5%	2660
December	1st to 10th	Night	69% 6% 9% 13% 3	2660
	11th to 20th	Night	64% 6% 9% 15% 6% 1	3288
	21st to end	Night	72% 5% 8% 13% 3	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	35% 13% 25% 23% 4	180
	11th to 20th	Day	27% 27% 28% 13% 4 1	180
	21st to end	Day	22% 17% 38% 17% 5%	214
February	1st to 10th	Day	31% 27% 29% 11% 2	270
	11th to 20th	Day	24% 26% 38% 11% 1	317
	21st to end	Day	31% 19% 34% 15% 2	382
March	1st to 10th	Day	27% 18% 30% 21% 4	460
	11th to 20th	Day	24% 22% 34% 16% 3 1	460
	21st to end	Day	29% 21% 26% 16% 7% 1	506
April	1st to 10th	Day	30% 19% 28% 17% 5% 1	460
	11th to 20th	Day	31% 21% 24% 16% 6% 2	452
	21st to end	Day	32% 15% 28% 16% 8% 1	460
May	1st to 10th	Day	27% 15% 30% 18% 8% 2	463
	11th to 20th	Day	18% 16% 33% 18% 11% 2	487
	21st to end	Day	19% 15% 31% 22% 11% 1	529
June	1st to 10th	Day	28% 11% 28% 22% 8% 3	490
	11th to 20th	Day	16% 13% 31% 28% 10% 2	490
	21st to end	Day	26% 14% 28% 18% 12% 2	490
July	1st to 10th	Day	14% 9% 26% 32% 14% 4	485
	11th to 20th	Day	14% 11% 30% 28% 15% 3	484
	21st to end	Day	16% 8% 31% 31% 13% 2	532
August	1st to 10th	Day	16% 8% 24% 34% 15% 3	486
	11th to 20th	Day	16% 7% 22% 32% 16% 7%	479
	21st to end	Day	16% 9% 29% 25% 13% 7%	539
September	1st to 10th	Day	15% 10% 30% 23% 14% 8%	490
	11th to 20th	Day	13% 8% 23% 24% 21% 11%	490
	21st to end	Day	19% 12% 32% 19% 14% 5%	490
October	1st to 10th	Day	25% 12% 27% 20% 12% 5%	490
	11th to 20th	Day	24% 19% 29% 19% 7% 1	490
	21st to end	Day	33% 16% 25% 20% 6%	421
November	1st to 10th	Day	26% 19% 28% 20% 7% 1	365
	11th to 20th	Day	25% 21% 35% 13% 7%	240
	21st to end	Day	28% 24% 27% 16% 4 1	180
December	1st to 10th	Day	31% 19% 27% 18% 4	180
	11th to 20th	Day	31% 27% 29% 12% 1 1	180
	21st to end	Day	32% 28% 23% 12% 4 1	198
January	1st to 10th	Night	28% 18% 31% 19% 4	760
	11th to 20th	Night	30% 15% 28% 21% 5% 1	760
	21st to end	Night	21% 14% 33% 26% 6%	836
February	1st to 10th	Night	23% 17% 35% 23% 3	760
	11th to 20th	Night	23% 17% 36% 19% 4	743
	21st to end	Night	25% 17% 29% 26% 3	628
March	1st to 10th	Night	26% 15% 30% 24% 5%	760
	11th to 20th	Night	27% 16% 34% 20% 4	760
	21st to end	Night	25% 14% 28% 26% 6%	836
April	1st to 10th	Night	29% 13% 30% 24% 4	760
	11th to 20th	Night	24% 16% 33% 21% 7%	751
	21st to end	Night	28% 11% 29% 23% 8% 1	664
May	1st to 10th	Night	27% 8% 30% 26% 8% 2	380
	11th to 20th	Night	23% 7% 32% 29% 8% 1	374
	21st to end	Night	14% 9% 38% 27% 11%	411
June	1st to 10th	Night	19% 7% 28% 37% 8%	380
	11th to 20th	Night	19% 7% 28% 32% 13% 1	380
	21st to end	Night	19% 4 30% 30% 14% 1	380
July	1st to 10th	Night	11% 7% 26% 40% 15% 1	370
	11th to 20th	Night	14% 4 26% 37% 18% 1	368
	21st to end	Night	13% 5% 28% 42% 12% 1	416
August	1st to 10th	Night	15% 4 20% 45% 15% 1	378
	11th to 20th	Night	14% 5% 20% 37% 22% 1	605
	21st to end	Night	16% 5% 25% 34% 18% 2	836
September	1st to 10th	Night	14% 8% 28% 33% 16% 1	760
	11th to 20th	Night	17% 6% 21% 31% 21% 4	760
	21st to end	Night	19% 8% 29% 23% 19% 2	760
October	1st to 10th	Night	24% 7% 29% 26% 14% 1	760
	11th to 20th	Night	25% 10% 31% 24% 9%	760
	21st to end	Night	29% 13% 28% 24% 6%	812
November	1st to 10th	Night	26% 15% 28% 22% 8% 1	740
	11th to 20th	Night	24% 17% 31% 19% 8% 1	760
	21st to end	Night	28% 16% 27% 21% 7%	760
December	1st to 10th	Night	30% 17% 29% 20% 3	760
	11th to 20th	Night	30% 16% 32% 17% 5% 1	760
	21st to end	Night	35% 15% 28% 18% 3	836

Page generated at 2024-10-22 20:21:00. Version ac07

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