St. Anthony
Clear Sky Chart
History

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

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	22% 14% 4 9% 5% 5% 4 3 5% 5% 24%	102055
	Night	20% 14% 4 9% 5% 4 4 4 5% 5% 24%	97267
Transparency	Day	60% 7% 12% 15% 6%	105460
	Night	61% 7% 12% 14% 6%	101975
Seeing	Day	28% 11% 27% 23% 9% 2	18203
	Night	28% 11% 28% 24% 8% 1	24974

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% 17% 6% 12% 6% 6% 5% 4 6% 5% 20%	2216
	11th to 20th	Day	18% 18% 7% 15% 7% 5% 4 4 5% 5% 13%	2353
	21st to end	Day	7% 12% 4 11% 7% 6% 6% 6% 7% 7% 26%	2783
February	1st to 10th	Day	13% 15% 5% 9% 5% 5% 6% 5% 5% 5% 27%	1520
	11th to 20th	Day	14% 18% 4 10% 6% 5% 4 3 5% 5% 26%	1616
	21st to end	Day	12% 16% 4 9% 6% 4 4 3 5% 6% 31%	1570
March	1st to 10th	Day	11% 11% 4 9% 6% 8% 6% 5% 6% 6% 27%	3114
	11th to 20th	Day	18% 22% 7% 13% 7% 5% 5% 2 3 4 15%	3342
	21st to end	Day	28% 14% 4 9% 4 3 4 2 3 4 23%	4029
April	1st to 10th	Day	21% 17% 5% 11% 6% 4 4 3 5% 5% 20%	2280
	11th to 20th	Day	19% 14% 5% 9% 6% 5% 4 3 5% 6% 25%	2436
	21st to end	Day	23% 15% 6% 10% 5% 4 3 4 5% 5% 22%	2474
May	1st to 10th	Day	26% 21% 6% 11% 6% 4 3 3 3 4 13%	4425
	11th to 20th	Day	21% 14% 5% 13% 6% 5% 5% 3 4 6% 18%	4664
	21st to end	Day	30% 15% 5% 8% 5% 3 4 2 4 4 20%	5173
June	1st to 10th	Day	33% 17% 3 7% 4 4 4 3 4 5% 16%	2850
	11th to 20th	Day	29% 14% 4 8% 4 3 4 3 4 5% 21%	2850
	21st to end	Day	24% 14% 4 8% 5% 4 5% 4 4 7% 22%	2850
July	1st to 10th	Day	21% 10% 3 8% 5% 5% 5% 4 6% 6% 28%	4750
	11th to 20th	Day	22% 13% 3 7% 4 4 3 3 4 5% 31%	4750
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 5% 6% 8% 32%	4921
August	1st to 10th	Day	25% 11% 3 8% 5% 4 4 3 5% 6% 25%	4424
	11th to 20th	Day	20% 11% 4 8% 6% 5% 5% 4 5% 6% 27%	4179
	21st to end	Day	18% 8% 3 7% 4 4 5% 4 6% 6% 35%	4532
September	1st to 10th	Day	25% 9% 3 6% 3 5% 4 3 4 6% 32%	2299
	11th to 20th	Day	26% 10% 4 7% 4 5% 4 3 5% 5% 25%	2116
	21st to end	Day	23% 11% 3 7% 4 5% 5% 3 5% 7% 28%	2090
October	1st to 10th	Day	24% 13% 3 7% 4 5% 4 3 5% 4 29%	2019
	11th to 20th	Day	25% 13% 4 7% 5% 4 5% 3 5% 5% 24%	1710
	21st to end	Day	23% 17% 5% 9% 4 4 4 2 4 5% 24%	1881
November	1st to 10th	Day	21% 14% 4 9% 5% 4 3 4 4 4 28%	1701
	11th to 20th	Day	20% 15% 5% 7% 6% 5% 3 2 3 5% 29%	1368
	21st to end	Day	25% 15% 6% 7% 4 4 5% 3 4 5% 23%	1330
December	1st to 10th	Day	18% 20% 6% 10% 6% 4 4 5% 5% 5% 18%	1330
	11th to 20th	Day	24% 14% 5% 9% 7% 7% 5% 4 5% 4 16%	1668
	21st to end	Day	22% 13% 3 9% 5% 4 5% 3 6% 6% 25%	2442
January	1st to 10th	Night	11% 16% 6% 12% 6% 5% 5% 4 5% 6% 23%	4739
	11th to 20th	Night	13% 15% 5% 17% 7% 5% 5% 4 5% 5% 18%	4613
	21st to end	Night	10% 12% 5% 10% 6% 5% 5% 9% 7% 6% 27%	4884
February	1st to 10th	Night	14% 12% 4 9% 7% 6% 5% 4 5% 6% 27%	2660
	11th to 20th	Night	15% 16% 5% 9% 7% 4 4 4 4 5% 26%	2448
	21st to end	Night	13% 12% 5% 9% 7% 5% 4 3 5% 6% 31%	1884
March	1st to 10th	Night	12% 14% 4 9% 7% 7% 7% 5% 6% 5% 26%	3726
	11th to 20th	Night	19% 19% 7% 14% 7% 5% 4 3 4 3 15%	3617
	21st to end	Night	25% 14% 5% 9% 5% 4 4 3 5% 5% 21%	3599
April	1st to 10th	Night	22% 16% 6% 11% 5% 5% 4 3 4 4 19%	1900
	11th to 20th	Night	21% 16% 4 9% 5% 4 4 3 5% 6% 24%	1692
	21st to end	Night	24% 14% 6% 7% 4 4 3 3 4 5% 25%	1705
May	1st to 10th	Night	30% 19% 5% 10% 5% 4 3 3 4 4 12%	2525
	11th to 20th	Night	25% 17% 4 13% 5% 4 4 3 3 4 19%	2238
	21st to end	Night	33% 17% 5% 9% 4 3 4 2 3 3 17%	2412
June	1st to 10th	Night	35% 15% 4 7% 5% 5% 4 3 4 4 15%	1330
	11th to 20th	Night	31% 12% 3 8% 5% 5% 4 3 5% 5% 18%	1330
	21st to end	Night	26% 15% 5% 8% 5% 4 5% 4 5% 6% 17%	1330
July	1st to 10th	Night	20% 11% 4 9% 5% 5% 4 5% 5% 6% 24%	2220
	11th to 20th	Night	25% 11% 3 7% 5% 4 4 4 5% 6% 26%	2220
	21st to end	Night	17% 10% 3 8% 4 4 4 4 6% 6% 34%	2641
August	1st to 10th	Night	20% 10% 3 7% 4 4 4 4 7% 8% 28%	2516
	11th to 20th	Night	23% 7% 4 7% 4 5% 5% 3 7% 6% 28%	2657
	21st to end	Night	18% 8% 3 6% 4 3 6% 4 6% 7% 34%	3135
September	1st to 10th	Night	24% 8% 2 7% 5% 4 4 3 5% 6% 32%	1877
	11th to 20th	Night	23% 11% 4 8% 5% 3 4 4 5% 5% 29%	2063
	21st to end	Night	23% 11% 4 7% 4 4 4 3 5% 6% 29%	2090
October	1st to 10th	Night	26% 12% 4 7% 4 4 3 4 4 5% 27%	2159
	11th to 20th	Night	21% 14% 3 9% 5% 4 4 4 5% 5% 27%	2470
	21st to end	Night	27% 13% 4 7% 5% 4 4 3 4 6% 22%	2717
November	1st to 10th	Night	22% 12% 4 9% 5% 5% 4 3 4 6% 26%	2595
	11th to 20th	Night	22% 15% 3 7% 4 4 3 4 5% 6% 26%	2819
	21st to end	Night	21% 18% 5% 9% 6% 4 4 3 4 5% 20%	2850
December	1st to 10th	Night	18% 19% 5% 10% 6% 5% 5% 3 4 4 20%	2850
	11th to 20th	Night	23% 16% 6% 9% 5% 5% 5% 3 5% 6% 18%	3531
	21st to end	Night	23% 13% 4 10% 5% 4 5% 3 5% 5% 22%	5225

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% 8% 10% 13% 4	2217
	11th to 20th	Day	72% 9% 9% 7% 3	2353
	21st to end	Day	53% 10% 11% 14% 11% 1	2783
February	1st to 10th	Day	57% 6% 11% 19% 7% 1	1520
	11th to 20th	Day	59% 6% 9% 15% 9% 1	1623
	21st to end	Day	53% 5% 8% 17% 16% 1	1570
March	1st to 10th	Day	52% 9% 11% 16% 10% 2	3118
	11th to 20th	Day	72% 7% 7% 9% 5% 1	3342
	21st to end	Day	63% 6% 8% 12% 11% 1	4029
April	1st to 10th	Day	64% 6% 8% 13% 8% 1	2280
	11th to 20th	Day	57% 8% 11% 14% 10%	2436
	21st to end	Day	63% 6% 9% 14% 7% 1	2474
May	1st to 10th	Day	72% 9% 8% 8% 3	4440
	11th to 20th	Day	63% 10% 10% 13% 4	4668
	21st to end	Day	65% 7% 10% 13% 4	5173
June	1st to 10th	Day	70% 6% 9% 10% 4	2850
	11th to 20th	Day	65% 7% 12% 14% 2	2850
	21st to end	Day	62% 8% 12% 14% 4 1	2850
July	1st to 10th	Day	55% 7% 16% 18% 4	4675
	11th to 20th	Day	55% 6% 16% 18% 5%	4668
	21st to end	Day	48% 7% 20% 22% 2	4764
August	1st to 10th	Day	60% 7% 14% 17% 3	4410
	11th to 20th	Day	55% 8% 17% 17% 3	4221
	21st to end	Day	47% 7% 17% 24% 6%	4532
September	1st to 10th	Day	51% 7% 15% 19% 8%	2299
	11th to 20th	Day	58% 8% 14% 15% 5%	2116
	21st to end	Day	54% 8% 15% 16% 6%	2090
October	1st to 10th	Day	57% 8% 14% 16% 5%	3347
	11th to 20th	Day	57% 7% 13% 15% 7%	2832
	21st to end	Day	62% 5% 10% 14% 8% 1	3092
November	1st to 10th	Day	60% 6% 12% 15% 7% 1	1701
	11th to 20th	Day	58% 7% 12% 16% 6% 1	1368
	21st to end	Day	64% 7% 9% 13% 7%	1330
December	1st to 10th	Day	67% 8% 10% 11% 4	1330
	11th to 20th	Day	71% 7% 9% 9% 3 1	1667
	21st to end	Day	60% 8% 12% 14% 6%	2442
January	1st to 10th	Night	61% 10% 9% 10% 8% 2	4739
	11th to 20th	Night	64% 10% 11% 11% 3	4613
	21st to end	Night	51% 9% 10% 17% 12%	4884
February	1st to 10th	Night	58% 6% 10% 16% 8% 1	2660
	11th to 20th	Night	60% 6% 12% 15% 7% 1	2452
	21st to end	Night	54% 7% 10% 17% 11% 1	1884
March	1st to 10th	Night	55% 8% 11% 17% 8% 1	3735
	11th to 20th	Night	73% 6% 7% 8% 6%	3618
	21st to end	Night	62% 7% 11% 13% 6% 1	3599
April	1st to 10th	Night	67% 6% 8% 11% 7%	1900
	11th to 20th	Night	59% 8% 10% 17% 7%	1692
	21st to end	Night	61% 4 10% 15% 9% 1	1705
May	1st to 10th	Night	74% 9% 8% 7% 2	2530
	11th to 20th	Night	66% 8% 8% 13% 6%	2239
	21st to end	Night	70% 8% 6% 13% 3	2413
June	1st to 10th	Night	72% 7% 6% 10% 4 1	1330
	11th to 20th	Night	66% 9% 13% 9% 3	1330
	21st to end	Night	66% 8% 9% 13% 4	1330
July	1st to 10th	Night	60% 6% 15% 15% 4	2186
	11th to 20th	Night	58% 6% 14% 18% 3 1	2178
	21st to end	Night	48% 7% 19% 23% 3	2558
August	1st to 10th	Night	52% 8% 20% 18% 1	2505
	11th to 20th	Night	53% 10% 18% 16% 4	2681
	21st to end	Night	47% 7% 18% 23% 6%	3134
September	1st to 10th	Night	52% 7% 16% 19% 6%	1877
	11th to 20th	Night	56% 8% 13% 18% 6%	2063
	21st to end	Night	54% 7% 15% 16% 7% 1	2090
October	1st to 10th	Night	66% 6% 11% 12% 5%	3614
	11th to 20th	Night	56% 7% 12% 16% 9%	4097
	21st to end	Night	60% 6% 14% 12% 7% 1	4467
November	1st to 10th	Night	58% 7% 14% 14% 6% 1	2595
	11th to 20th	Night	60% 6% 13% 16% 4	2819
	21st to end	Night	67% 7% 10% 10% 5%	2850
December	1st to 10th	Night	67% 8% 10% 11% 4	2850
	11th to 20th	Night	69% 7% 11% 9% 3	3533
	21st to end	Night	64% 9% 9% 11% 6%	5225

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% 17% 29% 21% 8% 2	370
	11th to 20th	Day	24% 19% 32% 16% 9% 1	370
	21st to end	Day	20% 18% 34% 22% 6% 1	407
February	1st to 10th	Day	22% 13% 34% 22% 6% 3	370
	11th to 20th	Day	21% 17% 37% 19% 5% 1	366
	21st to end	Day	19% 17% 36% 18% 8% 2	307
March	1st to 10th	Day	19% 16% 35% 21% 8% 1	370
	11th to 20th	Day	24% 12% 26% 22% 13% 3	370
	21st to end	Day	28% 14% 29% 21% 5% 2	466
April	1st to 10th	Day	27% 16% 29% 19% 6% 2	460
	11th to 20th	Day	26% 10% 28% 23% 9% 3	634
	21st to end	Day	29% 10% 26% 25% 8% 2	650
May	1st to 10th	Day	36% 10% 23% 19% 9% 3	653
	11th to 20th	Day	28% 9% 26% 21% 13% 3	674
	21st to end	Day	35% 9% 27% 21% 7% 1	735
June	1st to 10th	Day	43% 9% 18% 21% 8% 2	680
	11th to 20th	Day	35% 6% 23% 24% 10% 2	680
	21st to end	Day	28% 6% 25% 26% 12% 3	680
July	1st to 10th	Day	31% 5% 24% 26% 12% 3	670
	11th to 20th	Day	26% 6% 24% 32% 10% 2	668
	21st to end	Day	26% 4 24% 33% 11% 2	740
August	1st to 10th	Day	31% 4 22% 28% 13% 2	675
	11th to 20th	Day	27% 4 22% 33% 12% 2	667
	21st to end	Day	26% 7% 23% 28% 13% 3	748
September	1st to 10th	Day	28% 9% 29% 24% 9% 1	509
	11th to 20th	Day	33% 9% 26% 24% 6% 1	403
	21st to end	Day	27% 12% 33% 21% 6% 2	390
October	1st to 10th	Day	26% 14% 32% 22% 5% 1	390
	11th to 20th	Day	31% 10% 25% 21% 13% 1	390
	21st to end	Day	28% 14% 29% 20% 8% 1	429
November	1st to 10th	Day	30% 17% 33% 17% 2 1	395
	11th to 20th	Day	26% 17% 27% 21% 8% 1	370
	21st to end	Day	33% 16% 30% 17% 3	370
December	1st to 10th	Day	29% 14% 29% 19% 8% 1	370
	11th to 20th	Day	25% 19% 33% 18% 4 1	370
	21st to end	Day	28% 14% 31% 19% 5% 2	407
January	1st to 10th	Night	27% 18% 30% 16% 7% 1	850
	11th to 20th	Night	20% 16% 35% 21% 6% 1	850
	21st to end	Night	23% 17% 34% 23% 3	935
February	1st to 10th	Night	21% 15% 31% 25% 6% 1	850
	11th to 20th	Night	23% 16% 35% 20% 5% 1	815
	21st to end	Night	19% 10% 35% 26% 8% 2	628
March	1st to 10th	Night	19% 18% 33% 22% 7% 1	760
	11th to 20th	Night	23% 10% 28% 30% 7% 1	656
	21st to end	Night	29% 14% 31% 19% 6% 1	627
April	1st to 10th	Night	28% 10% 32% 20% 8% 2	570
	11th to 20th	Night	28% 10% 29% 23% 9% 1	564
	21st to end	Night	32% 7% 28% 24% 8% 1	570
May	1st to 10th	Night	36% 6% 20% 24% 10% 3	570
	11th to 20th	Night	33% 7% 25% 20% 14% 1	562
	21st to end	Night	35% 9% 25% 22% 9%	616
June	1st to 10th	Night	43% 5% 19% 23% 9% 1	570
	11th to 20th	Night	38% 5% 20% 25% 12% 1	570
	21st to end	Night	30% 6% 22% 29% 13% 1	570
July	1st to 10th	Night	31% 4 23% 30% 11% 1	556
	11th to 20th	Night	25% 4 28% 32% 10% 1	552
	21st to end	Night	26% 5% 21% 32% 14% 1	623
August	1st to 10th	Night	30% 5% 18% 32% 14% 1	568
	11th to 20th	Night	27% 4 21% 34% 13% 1	562
	21st to end	Night	25% 5% 24% 32% 14% 1	627
September	1st to 10th	Night	28% 8% 28% 26% 10%	570
	11th to 20th	Night	27% 11% 32% 25% 4 1	570
	21st to end	Night	29% 9% 31% 22% 6% 2	570
October	1st to 10th	Night	33% 7% 30% 25% 5% 1	619
	11th to 20th	Night	29% 9% 24% 28% 9%	860
	21st to end	Night	34% 13% 26% 21% 5% 1	946
November	1st to 10th	Night	29% 16% 32% 19% 4 1	880
	11th to 20th	Night	29% 15% 28% 20% 7% 1	853
	21st to end	Night	29% 19% 31% 18% 3	850
December	1st to 10th	Night	28% 14% 31% 20% 6%	850
	11th to 20th	Night	29% 20% 29% 18% 4	850
	21st to end	Night	23% 15% 33% 22% 7% 1	935

Page generated at 2024-11-08 07:44:45. Version ac07

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