Isle Pierre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Isle Pierre clear sky chart from 2005-11-06 to 2024-02-10.

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	9% 11% 5% 9% 8% 5% 6% 6% 6% 7% 28%	77371
	Night	9% 11% 5% 9% 8% 5% 6% 6% 6% 7% 28%	81527
Transparency	Day	51% 8% 16% 18% 6% 1	77066
	Night	53% 8% 15% 17% 7% 1	81412
Seeing	Day	14% 12% 27% 27% 16% 3	15289
	Night	15% 10% 27% 29% 17% 2	23372

By Month

Percentage Cloud Cover NW (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	7% 14% 6% 12% 8% 6% 7% 6% 6% 6% 23%	2105
	11th to 20th	Day	6% 16% 6% 8% 8% 4 6% 6% 5% 6% 30%	2199
	21st to end	Day	7% 17% 8% 14% 10% 4 6% 6% 5% 6% 17%	2442
February	1st to 10th	Day	10% 14% 5% 9% 9% 4 5% 5% 5% 6% 28%	1521
	11th to 20th	Day	8% 9% 5% 11% 8% 4 6% 6% 7% 9% 25%	1575
	21st to end	Day	5% 12% 6% 10% 8% 4 5% 6% 5% 8% 31%	1332
March	1st to 10th	Day	7% 12% 6% 9% 9% 4 6% 5% 7% 8% 28%	1781
	11th to 20th	Day	6% 13% 6% 8% 9% 5% 7% 6% 7% 8% 25%	1980
	21st to end	Day	7% 13% 7% 11% 9% 4 7% 6% 6% 7% 24%	2247
April	1st to 10th	Day	6% 13% 6% 13% 11% 5% 7% 7% 6% 5% 22%	2168
	11th to 20th	Day	8% 14% 6% 11% 11% 6% 7% 5% 5% 6% 23%	2308
	21st to end	Day	11% 12% 6% 9% 8% 4 6% 5% 6% 6% 26%	2492
May	1st to 10th	Day	8% 14% 5% 9% 8% 5% 6% 5% 5% 7% 27%	2520
	11th to 20th	Day	11% 10% 4 8% 8% 4 7% 6% 6% 7% 29%	2608
	21st to end	Day	11% 9% 3 10% 9% 5% 7% 7% 6% 7% 26%	3024
June	1st to 10th	Day	11% 9% 5% 9% 8% 6% 6% 6% 6% 8% 26%	2880
	11th to 20th	Day	14% 10% 4 10% 9% 6% 6% 6% 6% 7% 24%	2880
	21st to end	Day	10% 8% 4 9% 8% 5% 7% 6% 6% 8% 28%	2880
July	1st to 10th	Day	12% 8% 4 7% 8% 4 7% 6% 6% 7% 31%	2873
	11th to 20th	Day	10% 8% 4 7% 7% 5% 6% 6% 8% 8% 31%	2700
	21st to end	Day	8% 5% 3 7% 7% 4 7% 6% 8% 7% 37%	2938
August	1st to 10th	Day	7% 6% 3 7% 6% 4 5% 6% 7% 9% 40%	2590
	11th to 20th	Day	7% 6% 2 6% 6% 4 6% 6% 7% 8% 41%	2418
	21st to end	Day	10% 9% 4 9% 7% 5% 7% 6% 7% 8% 28%	2574
September	1st to 10th	Day	10% 6% 3 8% 7% 4 6% 5% 7% 8% 35%	2178
	11th to 20th	Day	9% 8% 4 7% 7% 4 6% 6% 6% 8% 34%	2156
	21st to end	Day	14% 10% 4 8% 7% 4 5% 7% 7% 7% 27%	1897
October	1st to 10th	Day	13% 12% 3 7% 6% 5% 6% 6% 7% 8% 28%	1800
	11th to 20th	Day	12% 10% 5% 9% 8% 5% 6% 6% 5% 7% 27%	1800
	21st to end	Day	12% 10% 4 9% 7% 3 5% 6% 6% 7% 30%	1629
November	1st to 10th	Day	13% 14% 6% 8% 8% 5% 6% 4 5% 6% 25%	1488
	11th to 20th	Day	8% 13% 6% 10% 10% 6% 7% 7% 6% 8% 20%	1520
	21st to end	Day	8% 14% 5% 12% 11% 6% 7% 6% 5% 6% 20%	1196
December	1st to 10th	Day	12% 8% 5% 11% 8% 4 6% 6% 7% 8% 25%	1140
	11th to 20th	Day	10% 14% 7% 12% 8% 4 7% 5% 5% 7% 20%	1442
	21st to end	Day	5% 13% 5% 9% 9% 5% 8% 6% 6% 8% 27%	2090
January	1st to 10th	Night	7% 14% 6% 12% 9% 5% 7% 6% 6% 7% 20%	4857
	11th to 20th	Night	7% 11% 6% 11% 9% 5% 6% 4 5% 6% 30%	4699
	21st to end	Night	12% 19% 7% 11% 8% 5% 6% 6% 6% 6% 15%	5214
February	1st to 10th	Night	9% 15% 6% 11% 8% 5% 6% 5% 5% 5% 25%	2639
	11th to 20th	Night	7% 12% 5% 12% 8% 4 6% 6% 6% 9% 25%	2272
	21st to end	Night	6% 10% 5% 10% 8% 3 6% 6% 6% 7% 33%	1924
March	1st to 10th	Night	6% 12% 6% 9% 8% 5% 5% 6% 6% 7% 29%	2175
	11th to 20th	Night	7% 11% 5% 10% 8% 4 7% 6% 6% 6% 29%	1979
	21st to end	Night	5% 9% 5% 11% 9% 7% 7% 7% 7% 7% 25%	2109
April	1st to 10th	Night	6% 12% 4 10% 8% 5% 8% 6% 6% 7% 28%	1789
	11th to 20th	Night	7% 11% 5% 8% 8% 5% 8% 7% 7% 8% 27%	1601
	21st to end	Night	7% 10% 5% 8% 7% 4 6% 5% 4 7% 36%	1468
May	1st to 10th	Night	10% 11% 5% 8% 8% 4 6% 5% 8% 8% 28%	1440
	11th to 20th	Night	11% 7% 3 9% 7% 6% 5% 7% 5% 8% 31%	1285
	21st to end	Night	13% 10% 4 7% 6% 4 6% 6% 8% 8% 27%	1249
June	1st to 10th	Night	15% 8% 4 7% 7% 4 8% 5% 6% 9% 29%	1080
	11th to 20th	Night	11% 9% 5% 8% 8% 4 7% 5% 7% 8% 28%	1080
	21st to end	Night	7% 7% 4 8% 7% 5% 7% 8% 8% 10% 30%	1080
July	1st to 10th	Night	10% 7% 3 7% 7% 4 7% 6% 7% 9% 34%	1084
	11th to 20th	Night	9% 6% 3 7% 6% 4 5% 6% 8% 7% 39%	1260
	21st to end	Night	9% 5% 3 4 5% 3 5% 6% 7% 9% 44%	1379
August	1st to 10th	Night	6% 6% 3 3 5% 3 6% 4 6% 8% 51%	1348
	11th to 20th	Night	6% 4 2 4 7% 4 5% 5% 5% 9% 50%	1478
	21st to end	Night	12% 7% 3 8% 7% 4 5% 6% 6% 10% 32%	1782
September	1st to 10th	Night	9% 8% 3 6% 7% 4 5% 6% 7% 8% 37%	1782
	11th to 20th	Night	8% 6% 3 6% 7% 3 5% 5% 6% 6% 44%	1802
	21st to end	Night	13% 10% 4 8% 6% 4 6% 5% 6% 8% 32%	2063
October	1st to 10th	Night	10% 9% 5% 9% 8% 5% 6% 6% 6% 7% 31%	2160
	11th to 20th	Night	13% 11% 3 8% 7% 5% 6% 5% 6% 7% 28%	2160
	21st to end	Night	12% 12% 4 7% 7% 4 5% 6% 6% 6% 29%	2723
November	1st to 10th	Night	13% 12% 4 9% 9% 4 7% 6% 6% 6% 23%	2590
	11th to 20th	Night	8% 12% 6% 11% 9% 4 7% 7% 6% 7% 24%	2660
	21st to end	Night	9% 13% 6% 11% 11% 5% 5% 6% 7% 8% 20%	2960
December	1st to 10th	Night	10% 9% 5% 9% 8% 5% 7% 5% 7% 8% 28%	3040
	11th to 20th	Night	9% 16% 6% 11% 8% 5% 7% 6% 6% 6% 22%	3750
	21st to end	Night	5% 12% 5% 11% 11% 5% 6% 6% 6% 8% 24%	5566

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% 12% 10% 16% 3	2105
	11th to 20th	Day	52% 10% 15% 7% 11% 5%	2220
	21st to end	Day	64% 11% 10% 10% 3	2442
February	1st to 10th	Day	56% 7% 12% 13% 11% 1	1521
	11th to 20th	Day	55% 8% 16% 16% 4 1	1584
	21st to end	Day	51% 5% 16% 17% 8% 3	1332
March	1st to 10th	Day	51% 6% 13% 19% 9% 1	1781
	11th to 20th	Day	51% 6% 18% 17% 7%	1980
	21st to end	Day	55% 6% 16% 17% 6%	2247
April	1st to 10th	Day	57% 7% 13% 17% 5% 1	2168
	11th to 20th	Day	58% 5% 12% 19% 6%	2308
	21st to end	Day	54% 5% 14% 17% 9%	2492
May	1st to 10th	Day	54% 6% 14% 19% 6%	2520
	11th to 20th	Day	48% 7% 14% 20% 10% 1	2611
	21st to end	Day	51% 6% 15% 20% 6% 1	3025
June	1st to 10th	Day	51% 6% 15% 19% 8% 1	2880
	11th to 20th	Day	54% 7% 14% 19% 6%	2880
	21st to end	Day	47% 8% 17% 21% 7%	2880
July	1st to 10th	Day	46% 7% 17% 22% 8% 1	2794
	11th to 20th	Day	45% 7% 21% 23% 4	2619
	21st to end	Day	36% 9% 23% 25% 7%	2775
August	1st to 10th	Day	36% 7% 24% 27% 6%	2572
	11th to 20th	Day	34% 8% 25% 27% 7%	2418
	21st to end	Day	49% 8% 20% 19% 4	2574
September	1st to 10th	Day	41% 7% 26% 21% 5%	2178
	11th to 20th	Day	41% 8% 20% 24% 7%	2156
	21st to end	Day	50% 9% 17% 18% 4 1	1897
October	1st to 10th	Day	49% 9% 20% 18% 4	1800
	11th to 20th	Day	52% 8% 17% 19% 3	1800
	21st to end	Day	50% 8% 18% 19% 5%	1629
November	1st to 10th	Day	60% 7% 13% 14% 6%	1488
	11th to 20th	Day	60% 9% 15% 12% 5%	1520
	21st to end	Day	63% 10% 11% 13% 4	1196
December	1st to 10th	Day	57% 9% 14% 15% 5%	1140
	11th to 20th	Day	64% 9% 11% 11% 5%	1444
	21st to end	Day	54% 11% 13% 15% 6% 1	2090
January	1st to 10th	Night	60% 10% 12% 15% 3	4857
	11th to 20th	Night	56% 6% 12% 8% 12% 6%	4740
	21st to end	Night	69% 10% 9% 8% 4	5214
February	1st to 10th	Night	61% 7% 11% 11% 9% 1	2639
	11th to 20th	Night	56% 6% 16% 15% 7%	2274
	21st to end	Night	50% 6% 13% 19% 10% 2	1924
March	1st to 10th	Night	50% 8% 13% 18% 10% 1	2175
	11th to 20th	Night	51% 6% 13% 20% 9% 1	1980
	21st to end	Night	53% 7% 15% 19% 6%	2109
April	1st to 10th	Night	51% 7% 13% 21% 9% 1	1789
	11th to 20th	Night	52% 6% 11% 23% 7%	1601
	21st to end	Night	48% 5% 11% 22% 12% 1	1468
May	1st to 10th	Night	50% 6% 16% 20% 7%	1440
	11th to 20th	Night	49% 6% 14% 20% 11% 1	1285
	21st to end	Night	47% 8% 16% 22% 7%	1249
June	1st to 10th	Night	49% 8% 12% 20% 10% 1	1080
	11th to 20th	Night	52% 6% 15% 20% 7%	1080
	21st to end	Night	44% 9% 19% 23% 6%	1080
July	1st to 10th	Night	43% 8% 18% 20% 9% 1	1054
	11th to 20th	Night	40% 7% 20% 26% 6%	1218
	21st to end	Night	30% 10% 24% 26% 9%	1302
August	1st to 10th	Night	30% 7% 23% 30% 10%	1341
	11th to 20th	Night	29% 7% 22% 33% 8%	1478
	21st to end	Night	46% 8% 20% 21% 4 1	1782
September	1st to 10th	Night	41% 7% 20% 26% 6% 1	1782
	11th to 20th	Night	37% 7% 15% 32% 9%	1802
	21st to end	Night	47% 10% 14% 21% 9%	2063
October	1st to 10th	Night	48% 8% 20% 19% 5%	2160
	11th to 20th	Night	51% 8% 19% 18% 4	2160
	21st to end	Night	51% 8% 15% 20% 6%	2723
November	1st to 10th	Night	58% 8% 15% 14% 6%	2590
	11th to 20th	Night	57% 10% 14% 14% 6%	2660
	21st to end	Night	58% 7% 16% 13% 5%	2960
December	1st to 10th	Night	54% 10% 14% 17% 5%	3040
	11th to 20th	Night	64% 10% 12% 10% 5%	3747
	21st to end	Night	55% 11% 14% 13% 7% 1	5566

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	12% 12% 32% 24% 14% 6%	180
	11th to 20th	Day	13% 17% 28% 20% 18% 4	180
	21st to end	Day	18% 18% 26% 22% 13% 4	198
February	1st to 10th	Day	18% 19% 32% 21% 9% 2	241
	11th to 20th	Day	16% 13% 37% 22% 11% 1	335
	21st to end	Day	13% 18% 33% 24% 9% 4	280
March	1st to 10th	Day	12% 16% 30% 27% 14% 2	400
	11th to 20th	Day	14% 16% 31% 25% 14%	420
	21st to end	Day	16% 20% 26% 21% 13% 4	462
April	1st to 10th	Day	14% 17% 32% 24% 11% 2	420
	11th to 20th	Day	14% 17% 30% 22% 12% 5%	412
	21st to end	Day	14% 16% 33% 24% 10% 3	420
May	1st to 10th	Day	14% 14% 32% 23% 14% 2	423
	11th to 20th	Day	14% 9% 23% 32% 18% 3	577
	21st to end	Day	14% 9% 25% 27% 22% 3	787
June	1st to 10th	Day	15% 10% 27% 29% 15% 2	810
	11th to 20th	Day	17% 9% 26% 31% 14% 3	810
	21st to end	Day	12% 7% 27% 30% 20% 4	810
July	1st to 10th	Day	14% 7% 22% 30% 24% 4	789
	11th to 20th	Day	14% 9% 24% 26% 24% 4	618
	21st to end	Day	9% 8% 21% 34% 24% 4	684
August	1st to 10th	Day	8% 7% 20% 33% 27% 5%	530
	11th to 20th	Day	7% 11% 27% 30% 18% 7%	437
	21st to end	Day	15% 10% 27% 29% 14% 5%	495
September	1st to 10th	Day	14% 11% 29% 28% 14% 3	450
	11th to 20th	Day	13% 10% 27% 27% 18% 6%	450
	21st to end	Day	19% 14% 36% 18% 11% 2	450
October	1st to 10th	Day	21% 13% 24% 25% 13% 3	450
	11th to 20th	Day	17% 14% 34% 21% 13%	450
	21st to end	Day	19% 15% 30% 23% 10% 3	223
November	1st to 10th	Day	21% 20% 27% 19% 10% 3	180
	11th to 20th	Day	18% 15% 26% 21% 13% 7%	180
	21st to end	Day	16% 13% 32% 26% 8% 5%	180
December	1st to 10th	Day	13% 9% 22% 32% 20% 4	180
	11th to 20th	Day	9% 12% 29% 32% 16% 3	180
	21st to end	Day	15% 12% 29% 25% 15% 5%	198
January	1st to 10th	Night	17% 14% 30% 27% 10% 2	929
	11th to 20th	Night	15% 12% 32% 26% 13% 1	850
	21st to end	Night	16% 15% 30% 27% 12% 1	935
February	1st to 10th	Night	16% 17% 24% 27% 14% 3	783
	11th to 20th	Night	15% 13% 29% 29% 13% 1	704
	21st to end	Night	12% 11% 27% 32% 16% 2	592
March	1st to 10th	Night	12% 15% 26% 27% 17% 3	720
	11th to 20th	Night	13% 13% 29% 31% 14% 1	720
	21st to end	Night	11% 11% 23% 27% 23% 4	792
April	1st to 10th	Night	14% 10% 22% 33% 18% 3	709
	11th to 20th	Night	15% 7% 25% 30% 19% 4	533
	21st to end	Night	12% 8% 31% 32% 15% 1	388
May	1st to 10th	Night	14% 11% 27% 29% 17% 3	360
	11th to 20th	Night	14% 5% 20% 37% 22% 2	354
	21st to end	Night	17% 8% 21% 28% 23% 2	389
June	1st to 10th	Night	18% 6% 27% 31% 17% 2	360
	11th to 20th	Night	14% 5% 30% 29% 20% 2	360
	21st to end	Night	10% 5% 24% 36% 23% 2	360
July	1st to 10th	Night	14% 4 21% 36% 24% 1	350
	11th to 20th	Night	11% 5% 22% 34% 24% 2	348
	21st to end	Night	10% 4 19% 39% 22% 6%	394
August	1st to 10th	Night	7% 4 19% 32% 32% 6%	358
	11th to 20th	Night	9% 5% 20% 33% 29% 4	410
	21st to end	Night	15% 5% 22% 33% 22% 3	594
September	1st to 10th	Night	14% 5% 23% 31% 25% 2	702
	11th to 20th	Night	11% 7% 17% 30% 28% 7%	720
	21st to end	Night	18% 10% 27% 27% 17% 1	720
October	1st to 10th	Night	17% 9% 23% 31% 18% 3	720
	11th to 20th	Night	19% 9% 27% 27% 16% 2	720
	21st to end	Night	21% 12% 29% 27% 11% 1	792
November	1st to 10th	Night	21% 13% 30% 25% 10% 2	740
	11th to 20th	Night	16% 15% 32% 26% 10% 1	760
	21st to end	Night	16% 15% 32% 26% 9% 2	982
December	1st to 10th	Night	14% 10% 25% 33% 15% 2	1040
	11th to 20th	Night	16% 12% 30% 28% 13% 1	1040
	21st to end	Night	13% 12% 32% 29% 13% 1	1144

Page generated at 2024-02-07 03:11:56. Version ac07

Copyright 2024 Attilla Danko