Argyle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Argyle 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	23% 11% 4 8% 5% 4 4 3 5% 6% 28%	101701
	Night	22% 13% 4 10% 5% 4 4 3 4 5% 26%	97317
Transparency	Day	31% 46% 6% 10% 6% 1	105287
	Night	33% 46% 6% 10% 5%	101820
Seeing	Day	30% 17% 30% 16% 6% 1	16779
	Night	30% 15% 27% 21% 7% 1	24545

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	21% 16% 5% 16% 7% 5% 4 3 4 4 15%	2272
	11th to 20th	Day	20% 13% 7% 16% 8% 5% 5% 3 4 4 14%	2840
	21st to end	Day	21% 13% 6% 16% 6% 4 4 3 4 4 18%	3124
February	1st to 10th	Day	20% 17% 6% 13% 8% 5% 4 4 4 5% 13%	1710
	11th to 20th	Day	17% 15% 5% 15% 9% 6% 4 3 3 4 17%	1663
	21st to end	Day	13% 13% 6% 12% 8% 4 4 5% 5% 6% 24%	1527
March	1st to 10th	Day	28% 12% 4 8% 7% 4 3 2 4 5% 22%	3362
	11th to 20th	Day	18% 13% 4 10% 6% 4 4 3 6% 6% 26%	3480
	21st to end	Day	30% 11% 4 11% 5% 4 3 2 4 5% 22%	3816
April	1st to 10th	Day	24% 12% 3 6% 4 4 4 3 4 4 30%	2185
	11th to 20th	Day	20% 9% 3 6% 5% 3 3 4 4 6% 37%	2413
	21st to end	Day	23% 9% 2 5% 3 3 4 3 5% 6% 36%	2470
May	1st to 10th	Day	23% 10% 4 8% 5% 4 4 4 5% 7% 27%	4106
	11th to 20th	Day	20% 9% 3 7% 5% 5% 4 3 6% 7% 31%	4207
	21st to end	Day	21% 12% 4 7% 5% 4 4 3 4 6% 30%	4836
June	1st to 10th	Day	27% 8% 2 5% 4 4 3 3 4 6% 32%	2698
	11th to 20th	Day	22% 7% 3 6% 4 4 4 4 4 6% 37%	2850
	21st to end	Day	27% 10% 3 7% 4 4 4 3 5% 6% 27%	2850
July	1st to 10th	Day	30% 12% 3 5% 3 3 3 3 5% 5% 26%	4760
	11th to 20th	Day	34% 10% 3 7% 4 4 4 3 4 6% 22%	4393
	21st to end	Day	21% 9% 3 7% 4 4 5% 4 5% 8% 31%	4467
August	1st to 10th	Day	33% 11% 3 5% 3 4 4 3 5% 5% 24%	4105
	11th to 20th	Day	19% 8% 3 7% 5% 4 5% 4 5% 7% 33%	4045
	21st to end	Day	13% 6% 2 5% 4 4 4 3 6% 7% 46%	4468
September	1st to 10th	Day	16% 7% 2 7% 3 3 3 3 5% 6% 43%	2266
	11th to 20th	Day	18% 7% 2 6% 3 3 3 3 3 6% 45%	2090
	21st to end	Day	19% 8% 2 7% 3 3 3 3 4 6% 41%	2090
October	1st to 10th	Day	19% 7% 3 6% 4 4 4 3 6% 7% 38%	1919
	11th to 20th	Day	20% 8% 2 6% 4 5% 4 3 7% 6% 35%	1900
	21st to end	Day	20% 10% 4 8% 5% 4 4 3 5% 6% 31%	2057
November	1st to 10th	Day	23% 8% 3 8% 4 4 3 4 4 5% 33%	1675
	11th to 20th	Day	21% 14% 5% 9% 6% 4 3 4 4 6% 23%	1520
	21st to end	Day	20% 16% 6% 10% 7% 4 4 4 5% 6% 19%	1520
December	1st to 10th	Day	25% 18% 5% 11% 5% 4 4 3 4 4 16%	1520
	11th to 20th	Day	28% 16% 5% 10% 6% 5% 4 3 4 5% 13%	1906
	21st to end	Day	24% 13% 7% 11% 6% 4 4 3 5% 5% 19%	2591
January	1st to 10th	Night	17% 16% 6% 21% 7% 5% 4 2 3 4 14%	4672
	11th to 20th	Night	19% 16% 7% 16% 8% 6% 4 3 3 4 14%	4120
	21st to end	Night	19% 16% 5% 16% 7% 6% 4 3 4 4 16%	4532
February	1st to 10th	Night	21% 16% 6% 15% 9% 5% 4 3 3 4 15%	2470
	11th to 20th	Night	19% 14% 5% 12% 9% 6% 5% 4 4 4 18%	2403
	21st to end	Night	14% 13% 5% 10% 7% 6% 5% 4 5% 6% 25%	1922
March	1st to 10th	Night	25% 12% 4 11% 8% 4 4 2 3 4 24%	3477
	11th to 20th	Night	16% 15% 5% 10% 5% 5% 4 4 5% 6% 25%	3479
	21st to end	Night	32% 11% 4 9% 3 3 2 2 3 4 26%	3816
April	1st to 10th	Night	23% 13% 3 7% 5% 3 3 3 4 6% 29%	1995
	11th to 20th	Night	23% 10% 3 6% 4 4 4 3 5% 7% 33%	1712
	21st to end	Night	25% 8% 2 6% 4 4 4 3 5% 7% 32%	1710
May	1st to 10th	Night	22% 13% 3 6% 5% 3 4 3 5% 8% 28%	2834
	11th to 20th	Night	22% 11% 3 8% 5% 4 4 3 5% 6% 28%	2675
	21st to end	Night	21% 13% 3 7% 5% 4 3 3 4 6% 30%	2749
June	1st to 10th	Night	27% 10% 3 7% 3 3 4 4 5% 7% 27%	1496
	11th to 20th	Night	19% 11% 4 6% 5% 4 4 3 5% 5% 34%	1330
	21st to end	Night	30% 13% 3 7% 4 4 3 3 4 5% 24%	1330
July	1st to 10th	Night	36% 12% 2 6% 4 3 3 3 5% 5% 19%	2210
	11th to 20th	Night	37% 14% 2 6% 4 3 3 3 4 4 20%	2532
	21st to end	Night	21% 12% 3 8% 5% 4 4 4 5% 7% 28%	3087
August	1st to 10th	Night	32% 14% 3 6% 4 3 3 2 3 5% 25%	2825
	11th to 20th	Night	22% 12% 3 10% 4 3 3 3 5% 6% 29%	2782
	21st to end	Night	14% 10% 3 6% 3 3 3 3 4 6% 43%	3188
September	1st to 10th	Night	19% 8% 2 5% 3 4 4 4 6% 6% 40%	1911
	11th to 20th	Night	21% 7% 2 5% 3 4 3 3 4 6% 42%	2090
	21st to end	Night	22% 8% 3 6% 4 3 3 4 4 6% 37%	2090
October	1st to 10th	Night	20% 7% 2 6% 4 4 3 3 5% 7% 38%	2261
	11th to 20th	Night	18% 8% 2 6% 4 3 3 3 6% 7% 40%	2280
	21st to end	Night	24% 9% 3 7% 4 4 3 3 5% 6% 33%	2537
November	1st to 10th	Night	19% 9% 3 7% 5% 4 4 4 5% 7% 34%	2476
	11th to 20th	Night	20% 13% 4 9% 6% 5% 4 4 5% 6% 24%	2660
	21st to end	Night	20% 15% 5% 9% 5% 5% 4 3 5% 5% 23%	2660
December	1st to 10th	Night	26% 15% 5% 9% 6% 5% 4 4 5% 5% 15%	2660
	11th to 20th	Night	26% 15% 5% 11% 6% 4 4 3 4 5% 16%	3293
	21st to end	Night	24% 15% 5% 11% 5% 5% 4 3 4 4 22%	5053

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	48% 36% 9% 7% 1	2273
	11th to 20th	Day	47% 37% 6% 8% 3	2840
	21st to end	Day	45% 39% 6% 6% 5%	3124
February	1st to 10th	Day	26% 65% 3 3 2	1710
	11th to 20th	Day	25% 64% 2 6% 3	1671
	21st to end	Day	19% 66% 3 7% 4 1	1527
March	1st to 10th	Day	42% 39% 5% 9% 4 1	3366
	11th to 20th	Day	39% 38% 8% 9% 5%	3480
	21st to end	Day	47% 39% 3 6% 5% 1	3816
April	1st to 10th	Day	23% 64% 3 6% 4	2185
	11th to 20th	Day	17% 66% 5% 8% 4	2413
	21st to end	Day	18% 64% 3 7% 7% 1	2470
May	1st to 10th	Day	35% 39% 8% 15% 2	4120
	11th to 20th	Day	36% 39% 10% 12% 3	4211
	21st to end	Day	38% 39% 6% 7% 9%	4836
June	1st to 10th	Day	18% 65% 3 9% 6%	2698
	11th to 20th	Day	15% 65% 5% 8% 6% 1	2850
	21st to end	Day	19% 64% 4 8% 5% 1	2850
July	1st to 10th	Day	39% 37% 4 10% 8% 1	4685
	11th to 20th	Day	40% 37% 6% 11% 6%	4313
	21st to end	Day	32% 38% 7% 14% 8% 1	4325
August	1st to 10th	Day	41% 38% 4 10% 6%	4092
	11th to 20th	Day	30% 42% 9% 17% 3	4084
	21st to end	Day	19% 39% 8% 18% 15% 2	4468
September	1st to 10th	Day	16% 60% 5% 11% 7% 1	2266
	11th to 20th	Day	19% 60% 4 9% 7% 1	2090
	21st to end	Day	17% 60% 4 11% 8% 1	2090
October	1st to 10th	Day	28% 40% 7% 17% 7% 1	3192
	11th to 20th	Day	24% 38% 5% 16% 16% 1	3140
	21st to end	Day	26% 37% 8% 19% 7% 3	3371
November	1st to 10th	Day	24% 59% 5% 8% 3 1	1675
	11th to 20th	Day	27% 59% 5% 7% 3	1520
	21st to end	Day	28% 60% 4 7% 1	1520
December	1st to 10th	Day	30% 59% 4 5% 1	1520
	11th to 20th	Day	39% 47% 6% 5% 3	1905
	21st to end	Day	43% 36% 13% 5% 3	2591
January	1st to 10th	Night	50% 36% 5% 8% 1	4672
	11th to 20th	Night	49% 36% 4 7% 3	4120
	21st to end	Night	46% 38% 6% 7% 3	4532
February	1st to 10th	Night	27% 64% 3 3 2	2470
	11th to 20th	Night	23% 63% 3 7% 3	2406
	21st to end	Night	21% 65% 4 5% 4	1922
March	1st to 10th	Night	42% 40% 4 6% 7%	3486
	11th to 20th	Night	39% 39% 9% 8% 6%	3480
	21st to end	Night	46% 39% 4 6% 4 1	3816
April	1st to 10th	Night	21% 64% 3 6% 5% 2	1995
	11th to 20th	Night	20% 65% 3 9% 3 1	1712
	21st to end	Night	19% 65% 3 6% 5% 1	1710
May	1st to 10th	Night	35% 39% 11% 12% 3	2840
	11th to 20th	Night	37% 39% 9% 13% 2	2676
	21st to end	Night	36% 39% 7% 15% 3	2750
June	1st to 10th	Night	18% 66% 3 9% 5%	1496
	11th to 20th	Night	16% 65% 5% 9% 5%	1330
	21st to end	Night	20% 64% 3 7% 6% 1	1330
July	1st to 10th	Night	46% 36% 4 7% 7%	2175
	11th to 20th	Night	45% 37% 4 7% 7%	2489
	21st to end	Night	33% 39% 6% 13% 8% 1	2989
August	1st to 10th	Night	42% 38% 5% 10% 4	2813
	11th to 20th	Night	34% 41% 11% 13% 1	2809
	21st to end	Night	22% 40% 6% 17% 13% 1	3187
September	1st to 10th	Night	16% 61% 3 12% 7% 1	1911
	11th to 20th	Night	19% 59% 4 11% 6% 1	2090
	21st to end	Night	18% 60% 2 12% 7%	2090
October	1st to 10th	Night	31% 39% 8% 12% 8% 1	3768
	11th to 20th	Night	19% 37% 8% 18% 17% 1	3779
	21st to end	Night	25% 37% 8% 20% 10% 1	4173
November	1st to 10th	Night	24% 58% 6% 8% 4	2476
	11th to 20th	Night	24% 60% 5% 7% 3	2660
	21st to end	Night	26% 60% 6% 5% 3	2660
December	1st to 10th	Night	27% 60% 5% 6% 2	2660
	11th to 20th	Night	37% 49% 4 8% 2	3295
	21st to end	Night	42% 36% 9% 10% 2	5053

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	41% 22% 28% 7% 2	181
	11th to 20th	Day	36% 22% 28% 12% 3	370
	21st to end	Day	27% 25% 34% 12% 2	407
February	1st to 10th	Day	36% 19% 31% 11% 3	370
	11th to 20th	Day	34% 30% 24% 10% 2	366
	21st to end	Day	32% 22% 29% 14% 2	361
March	1st to 10th	Day	34% 22% 32% 10% 3	460
	11th to 20th	Day	37% 22% 26% 9% 5%	460
	21st to end	Day	32% 25% 26% 11% 5% 1	506
April	1st to 10th	Day	39% 24% 24% 9% 3	460
	11th to 20th	Day	32% 21% 34% 10% 3	452
	21st to end	Day	32% 20% 30% 12% 5% 1	460
May	1st to 10th	Day	33% 23% 29% 12% 3 1	463
	11th to 20th	Day	25% 22% 28% 19% 5% 1	561
	21st to end	Day	30% 15% 31% 18% 6% 1	735
June	1st to 10th	Day	31% 16% 27% 20% 6% 1	680
	11th to 20th	Day	23% 14% 33% 21% 7% 1	680
	21st to end	Day	36% 11% 27% 18% 6% 1	680
July	1st to 10th	Day	29% 8% 30% 22% 9% 1	670
	11th to 20th	Day	28% 8% 32% 23% 7% 2	585
	21st to end	Day	24% 11% 38% 20% 8% 1	532
August	1st to 10th	Day	24% 9% 33% 24% 7% 2	486
	11th to 20th	Day	25% 12% 34% 17% 10% 2	479
	21st to end	Day	24% 13% 29% 20% 11% 4	539
September	1st to 10th	Day	19% 14% 34% 23% 8% 2	490
	11th to 20th	Day	25% 11% 30% 21% 8% 4	490
	21st to end	Day	22% 14% 32% 21% 7% 4	490
October	1st to 10th	Day	25% 13% 28% 22% 10% 3	400
	11th to 20th	Day	26% 17% 28% 19% 7% 3	390
	21st to end	Day	29% 20% 30% 16% 6%	429
November	1st to 10th	Day	28% 19% 29% 16% 7% 1	374
	11th to 20th	Day	36% 20% 26% 13% 5% 1	370
	21st to end	Day	34% 21% 30% 12% 2 1	370
December	1st to 10th	Day	36% 20% 30% 11% 2	370
	11th to 20th	Day	42% 26% 21% 10% 1	370
	21st to end	Day	42% 24% 21% 10% 3 1	293
January	1st to 10th	Night	33% 21% 29% 13% 3	830
	11th to 20th	Night	36% 16% 29% 16% 3	760
	21st to end	Night	28% 23% 31% 16% 3	836
February	1st to 10th	Night	35% 18% 29% 18% 1	760
	11th to 20th	Night	33% 24% 25% 14% 3	743
	21st to end	Night	25% 20% 33% 17% 5%	628
March	1st to 10th	Night	29% 20% 31% 16% 4	760
	11th to 20th	Night	28% 18% 28% 20% 6% 1	760
	21st to end	Night	28% 18% 30% 18% 6% 1	836
April	1st to 10th	Night	34% 17% 29% 17% 2	665
	11th to 20th	Night	29% 17% 33% 18% 4	564
	21st to end	Night	31% 14% 27% 20% 7%	570
May	1st to 10th	Night	28% 14% 32% 21% 4 1	570
	11th to 20th	Night	28% 10% 33% 23% 5%	562
	21st to end	Night	27% 10% 30% 27% 4 1	616
June	1st to 10th	Night	32% 8% 29% 22% 8%	546
	11th to 20th	Night	22% 7% 31% 32% 7% 1	380
	21st to end	Night	34% 5% 23% 28% 9%	380
July	1st to 10th	Night	29% 5% 25% 29% 11%	370
	11th to 20th	Night	27% 6% 26% 30% 11% 1	471
	21st to end	Night	26% 8% 26% 31% 8%	623
August	1st to 10th	Night	26% 6% 25% 32% 10% 1	568
	11th to 20th	Night	28% 8% 22% 29% 12%	562
	21st to end	Night	22% 5% 26% 30% 15% 1	627
September	1st to 10th	Night	22% 8% 27% 31% 12% 1	581
	11th to 20th	Night	25% 9% 24% 24% 16% 2	760
	21st to end	Night	27% 9% 26% 25% 12% 2	760
October	1st to 10th	Night	26% 9% 26% 26% 12% 1	760
	11th to 20th	Night	25% 15% 27% 23% 8% 2	760
	21st to end	Night	31% 15% 26% 23% 5%	836
November	1st to 10th	Night	28% 12% 28% 23% 8% 1	766
	11th to 20th	Night	31% 18% 26% 19% 6%	850
	21st to end	Night	32% 20% 24% 18% 6%	850
December	1st to 10th	Night	36% 17% 28% 15% 3	850
	11th to 20th	Night	37% 23% 25% 13% 2	850
	21st to end	Night	36% 21% 22% 18% 3	935

Page generated at 2024-11-01 23:47:39. Version ac07

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