Pelican Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pelican Point clear sky chart from 2005-11-06 to 2024-01-14.

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	10% 8% 4 7% 7% 4 6% 5% 6% 8% 35%	74646
	Night	9% 9% 4 8% 7% 4 6% 6% 6% 8% 34%	75126
Transparency	Day	45% 8% 16% 22% 8% 1	74327
	Night	46% 8% 15% 21% 9% 1	74963
Seeing	Day	13% 6% 24% 31% 20% 6%	14305
	Night	13% 5% 28% 36% 15% 2	23533

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	6% 12% 6% 9% 10% 6% 6% 4 6% 8% 27%	1329
	11th to 20th	Day	6% 10% 6% 9% 9% 3 5% 7% 6% 8% 29%	1281
	21st to end	Day	6% 13% 6% 10% 10% 4 7% 6% 6% 7% 23%	1503
February	1st to 10th	Day	9% 12% 4 11% 7% 5% 5% 4 6% 10% 27%	1440
	11th to 20th	Day	8% 12% 5% 11% 9% 4 8% 6% 7% 6% 25%	1571
	21st to end	Day	5% 9% 6% 11% 8% 4 7% 7% 7% 8% 26%	1371
March	1st to 10th	Day	8% 12% 5% 10% 9% 6% 7% 6% 6% 7% 25%	1804
	11th to 20th	Day	8% 11% 5% 8% 7% 4 5% 6% 7% 7% 33%	1979
	21st to end	Day	9% 13% 5% 10% 8% 4 6% 5% 6% 8% 25%	2178
April	1st to 10th	Day	10% 10% 4 8% 8% 5% 6% 6% 6% 7% 30%	2253
	11th to 20th	Day	13% 11% 4 8% 7% 4 6% 5% 6% 6% 31%	2310
	21st to end	Day	13% 9% 3 6% 6% 4 5% 5% 6% 10% 32%	2340
May	1st to 10th	Day	11% 10% 4 8% 7% 3 5% 7% 7% 7% 29%	2562
	11th to 20th	Day	9% 6% 2 6% 5% 5% 6% 6% 6% 8% 41%	2654
	21st to end	Day	18% 7% 3 7% 5% 4 4 5% 6% 7% 33%	2917
June	1st to 10th	Day	16% 6% 3 6% 6% 3 6% 5% 8% 9% 32%	2700
	11th to 20th	Day	20% 8% 4 7% 7% 4 5% 5% 7% 8% 25%	2700
	21st to end	Day	10% 5% 3 5% 5% 3 6% 6% 7% 10% 40%	2700
July	1st to 10th	Day	11% 5% 2 5% 5% 4 6% 5% 7% 8% 43%	2700
	11th to 20th	Day	12% 4 2 4 5% 3 6% 6% 7% 9% 42%	2700
	21st to end	Day	8% 4 2 5% 5% 3 5% 5% 5% 9% 49%	2938
August	1st to 10th	Day	10% 5% 2 5% 6% 4 5% 5% 7% 9% 42%	2564
	11th to 20th	Day	10% 4 2 5% 5% 3 4 5% 7% 9% 45%	2325
	21st to end	Day	10% 5% 2 5% 4 3 5% 5% 6% 9% 45%	2574
September	1st to 10th	Day	13% 5% 2 5% 6% 3 5% 5% 6% 7% 44%	2278
	11th to 20th	Day	15% 8% 2 5% 5% 2 4 3 5% 7% 43%	1980
	21st to end	Day	10% 7% 3 5% 5% 3 4 4 7% 9% 45%	1980
October	1st to 10th	Day	13% 10% 3 6% 6% 3 5% 4 4 5% 41%	1859
	11th to 20th	Day	9% 9% 4 6% 6% 3 4 5% 5% 8% 41%	1689
	21st to end	Day	9% 11% 4 8% 7% 4 6% 6% 6% 8% 31%	1760
November	1st to 10th	Day	10% 14% 7% 10% 8% 3 7% 4 5% 7% 24%	1488
	11th to 20th	Day	7% 12% 5% 12% 6% 4 5% 6% 5% 8% 30%	1435
	21st to end	Day	7% 8% 5% 11% 8% 4 6% 6% 5% 8% 32%	1330
December	1st to 10th	Day	8% 11% 4 12% 11% 6% 7% 5% 6% 6% 24%	1330
	11th to 20th	Day	6% 9% 6% 12% 7% 5% 8% 7% 7% 7% 26%	1682
	21st to end	Day	5% 7% 3 8% 7% 3 4 5% 6% 8% 44%	2442
January	1st to 10th	Night	5% 11% 5% 11% 10% 5% 6% 6% 7% 8% 26%	2836
	11th to 20th	Night	7% 10% 5% 8% 8% 5% 6% 6% 6% 9% 30%	2758
	21st to end	Night	7% 13% 6% 10% 7% 4 6% 6% 6% 7% 27%	2870
February	1st to 10th	Night	6% 9% 7% 10% 9% 6% 6% 5% 6% 7% 28%	2520
	11th to 20th	Night	7% 13% 6% 8% 7% 5% 7% 7% 7% 7% 26%	2275
	21st to end	Night	6% 10% 6% 7% 7% 4 6% 6% 6% 10% 32%	1884
March	1st to 10th	Night	6% 11% 5% 9% 9% 5% 6% 6% 7% 9% 28%	2156
	11th to 20th	Night	6% 11% 5% 9% 7% 4 6% 7% 6% 9% 30%	1980
	21st to end	Night	9% 11% 6% 10% 7% 5% 6% 6% 7% 8% 25%	2178
April	1st to 10th	Night	8% 9% 4 9% 6% 4 5% 6% 6% 9% 33%	1705
	11th to 20th	Night	11% 9% 5% 8% 6% 4 6% 5% 7% 9% 29%	1601
	21st to end	Night	13% 9% 4 6% 6% 3 5% 5% 6% 8% 34%	1620
May	1st to 10th	Night	15% 10% 4 7% 6% 4 6% 5% 6% 8% 29%	1396
	11th to 20th	Night	11% 8% 3 7% 6% 5% 5% 6% 5% 8% 35%	1239
	21st to end	Night	22% 7% 2 5% 6% 3 5% 4 7% 7% 32%	1358
June	1st to 10th	Night	17% 7% 3 7% 6% 5% 5% 6% 7% 8% 29%	1260
	11th to 20th	Night	17% 9% 4 8% 7% 4 6% 6% 6% 7% 27%	1260
	21st to end	Night	8% 4 3 5% 5% 4 6% 7% 10% 10% 37%	1260
July	1st to 10th	Night	11% 5% 2 5% 5% 3 5% 5% 7% 11% 41%	1260
	11th to 20th	Night	11% 4 2 4 6% 3 6% 5% 7% 11% 39%	1260
	21st to end	Night	9% 4 2 5% 5% 3 5% 5% 7% 9% 47%	1379
August	1st to 10th	Night	9% 6% 3 5% 6% 4 6% 7% 6% 10% 38%	1373
	11th to 20th	Night	10% 6% 2 6% 4 4 4 6% 7% 8% 42%	1576
	21st to end	Night	9% 4 3 5% 5% 4 5% 5% 6% 7% 45%	1782
September	1st to 10th	Night	12% 5% 3 6% 6% 3 5% 5% 5% 8% 43%	1679
	11th to 20th	Night	14% 6% 2 5% 5% 2 5% 4 4 7% 45%	1980
	21st to end	Night	9% 7% 3 5% 6% 2 4 4 6% 9% 44%	1980
October	1st to 10th	Night	11% 8% 3 7% 6% 3 4 4 6% 8% 40%	2101
	11th to 20th	Night	9% 8% 4 7% 6% 4 5% 6% 6% 7% 38%	2268
	21st to end	Night	8% 11% 3 7% 8% 4 6% 6% 6% 8% 33%	2577
November	1st to 10th	Night	10% 14% 6% 7% 6% 3 5% 5% 6% 8% 29%	2590
	11th to 20th	Night	8% 12% 5% 9% 7% 4 6% 6% 6% 8% 30%	2741
	21st to end	Night	6% 9% 6% 10% 9% 3 6% 6% 6% 8% 30%	2850
December	1st to 10th	Night	8% 12% 6% 10% 9% 4 5% 5% 5% 8% 28%	2850
	11th to 20th	Night	6% 10% 5% 11% 9% 4 6% 5% 6% 10% 29%	3510
	21st to end	Night	4 8% 4 7% 6% 3 5% 5% 6% 9% 43%	5214

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	55% 7% 10% 20% 8% 1	1329
	11th to 20th	Day	49% 8% 15% 17% 9% 1	1281
	21st to end	Day	57% 8% 13% 15% 7% 1	1503
February	1st to 10th	Day	53% 6% 13% 17% 10% 1	1440
	11th to 20th	Day	55% 7% 13% 16% 8%	1580
	21st to end	Day	52% 7% 12% 18% 9%	1371
March	1st to 10th	Day	57% 8% 14% 16% 4	1804
	11th to 20th	Day	46% 8% 13% 22% 10%	1980
	21st to end	Day	55% 8% 16% 15% 5% 1	2178
April	1st to 10th	Day	50% 8% 15% 17% 9% 1	2253
	11th to 20th	Day	52% 6% 13% 19% 10% 1	2310
	21st to end	Day	47% 8% 15% 21% 8% 2	2340
May	1st to 10th	Day	50% 8% 13% 20% 8%	2562
	11th to 20th	Day	40% 8% 13% 27% 11% 1	2658
	21st to end	Day	48% 8% 14% 20% 10%	2918
June	1st to 10th	Day	46% 9% 15% 22% 7%	2700
	11th to 20th	Day	55% 9% 14% 17% 4 1	2700
	21st to end	Day	37% 10% 25% 21% 6% 1	2700
July	1st to 10th	Day	38% 9% 21% 25% 6% 1	2626
	11th to 20th	Day	38% 10% 22% 26% 4	2619
	21st to end	Day	33% 10% 23% 29% 6%	2775
August	1st to 10th	Day	38% 10% 22% 25% 5%	2546
	11th to 20th	Day	34% 9% 25% 24% 8%	2325
	21st to end	Day	34% 9% 21% 26% 10% 1	2574
September	1st to 10th	Day	39% 7% 18% 26% 8% 2	2278
	11th to 20th	Day	42% 5% 16% 28% 8% 1	1980
	21st to end	Day	36% 8% 18% 26% 11% 2	1980
October	1st to 10th	Day	46% 5% 17% 21% 10% 1	1859
	11th to 20th	Day	40% 7% 18% 23% 10% 1	1689
	21st to end	Day	49% 8% 12% 22% 9% 1	1760
November	1st to 10th	Day	59% 6% 11% 16% 7% 1	1488
	11th to 20th	Day	52% 7% 15% 20% 6%	1435
	21st to end	Day	48% 8% 17% 19% 7% 1	1330
December	1st to 10th	Day	59% 6% 11% 15% 7% 2	1330
	11th to 20th	Day	52% 9% 15% 18% 5% 1	1684
	21st to end	Day	38% 6% 10% 26% 17% 3	2442
January	1st to 10th	Night	53% 6% 15% 16% 7% 2	2836
	11th to 20th	Night	51% 7% 15% 16% 9% 2	2758
	21st to end	Night	54% 7% 13% 16% 9% 1	2870
February	1st to 10th	Night	53% 6% 13% 19% 9% 1	2520
	11th to 20th	Night	53% 8% 14% 16% 9%	2276
	21st to end	Night	46% 7% 14% 21% 11% 2	1884
March	1st to 10th	Night	50% 9% 13% 21% 7% 1	2156
	11th to 20th	Night	50% 6% 13% 20% 10% 1	1980
	21st to end	Night	53% 9% 14% 16% 8% 1	2178
April	1st to 10th	Night	46% 8% 14% 19% 12% 1	1705
	11th to 20th	Night	49% 7% 12% 20% 9% 2	1601
	21st to end	Night	46% 7% 13% 22% 10% 2	1620
May	1st to 10th	Night	51% 7% 10% 21% 9% 1	1396
	11th to 20th	Night	45% 7% 12% 22% 12% 1	1239
	21st to end	Night	50% 8% 11% 20% 9% 2	1358
June	1st to 10th	Night	49% 11% 13% 20% 7%	1260
	11th to 20th	Night	55% 8% 13% 17% 6% 1	1260
	21st to end	Night	37% 11% 22% 23% 6% 1	1260
July	1st to 10th	Night	36% 11% 20% 25% 7% 1	1225
	11th to 20th	Night	38% 12% 21% 22% 6%	1218
	21st to end	Night	32% 8% 23% 29% 8%	1302
August	1st to 10th	Night	40% 10% 20% 24% 6%	1366
	11th to 20th	Night	37% 9% 19% 27% 7% 1	1576
	21st to end	Night	35% 8% 18% 28% 10% 1	1782
September	1st to 10th	Night	38% 8% 15% 23% 12% 4	1679
	11th to 20th	Night	38% 7% 13% 29% 10% 3	1980
	21st to end	Night	36% 7% 13% 26% 14% 3	1980
October	1st to 10th	Night	43% 7% 15% 24% 11% 1	2101
	11th to 20th	Night	42% 8% 15% 24% 10% 1	2268
	21st to end	Night	47% 9% 15% 22% 7% 1	2577
November	1st to 10th	Night	51% 7% 13% 21% 7% 1	2590
	11th to 20th	Night	51% 7% 13% 20% 9% 1	2741
	21st to end	Night	49% 8% 16% 19% 7% 1	2850
December	1st to 10th	Night	54% 5% 11% 19% 9% 2	2850
	11th to 20th	Night	51% 7% 19% 17% 6%	3507
	21st to end	Night	37% 6% 14% 23% 16% 4	5214

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	7% 6% 29% 33% 19% 6%	180
	11th to 20th	Day	5% 4 29% 37% 22% 4	166
	21st to end	Day	12% 7% 33% 28% 13% 8%	176
February	1st to 10th	Day	15% 6% 29% 33% 13% 4	160
	11th to 20th	Day	14% 5% 31% 33% 16% 2	238
	21st to end	Day	7% 3 29% 35% 19% 7%	237
March	1st to 10th	Day	12% 8% 30% 29% 18% 3	420
	11th to 20th	Day	11% 3 32% 34% 13% 7%	420
	21st to end	Day	15% 6% 27% 33% 14% 5%	462
April	1st to 10th	Day	11% 11% 30% 30% 14% 4	420
	11th to 20th	Day	17% 8% 22% 30% 18% 5%	412
	21st to end	Day	17% 7% 27% 31% 15% 3	420
May	1st to 10th	Day	15% 8% 23% 29% 19% 6%	557
	11th to 20th	Day	10% 7% 22% 34% 21% 7%	625
	21st to end	Day	18% 4 20% 30% 20% 8%	679
June	1st to 10th	Day	18% 6% 21% 33% 16% 4	630
	11th to 20th	Day	20% 7% 25% 26% 18% 4	630
	21st to end	Day	12% 3 21% 31% 24% 9%	630
July	1st to 10th	Day	12% 4 15% 32% 28% 9%	621
	11th to 20th	Day	14% 5% 18% 33% 24% 6%	618
	21st to end	Day	7% 5% 17% 32% 30% 10%	684
August	1st to 10th	Day	11% 2 20% 30% 25% 11%	504
	11th to 20th	Day	11% 4 21% 28% 29% 8%	437
	21st to end	Day	11% 6% 16% 30% 26% 11%	495
September	1st to 10th	Day	13% 8% 26% 29% 20% 4	450
	11th to 20th	Day	18% 5% 26% 27% 19% 4	450
	21st to end	Day	14% 11% 24% 30% 17% 4	450
October	1st to 10th	Day	19% 6% 27% 24% 18% 6%	329
	11th to 20th	Day	11% 9% 27% 34% 16% 3	270
	21st to end	Day	12% 7% 34% 29% 14% 2	297
November	1st to 10th	Day	16% 6% 31% 30% 11% 4	270
	11th to 20th	Day	13% 7% 35% 33% 11% 1	230
	21st to end	Day	8% 7% 31% 32% 17% 6%	180
December	1st to 10th	Day	7% 6% 32% 31% 18% 6%	180
	11th to 20th	Day	8% 10% 29% 37% 13% 3	180
	21st to end	Day	6% 5% 23% 44% 18% 5%	198
January	1st to 10th	Night	9% 9% 32% 34% 15% 1	950
	11th to 20th	Night	12% 8% 30% 35% 13% 2	920
	21st to end	Night	14% 10% 31% 32% 10% 2	890
February	1st to 10th	Night	9% 9% 26% 36% 18% 3	720
	11th to 20th	Night	12% 7% 34% 33% 13% 1	704
	21st to end	Night	10% 4 24% 39% 19% 4	592
March	1st to 10th	Night	9% 5% 28% 39% 17% 2	720
	11th to 20th	Night	11% 4 31% 37% 14% 3	720
	21st to end	Night	16% 3 27% 37% 16% 2	792
April	1st to 10th	Night	9% 5% 29% 35% 17% 4	620
	11th to 20th	Night	15% 5% 31% 38% 10% 1	533
	21st to end	Night	18% 6% 25% 36% 14%	540
May	1st to 10th	Night	17% 4 25% 38% 13% 2	450
	11th to 20th	Night	14% 5% 23% 38% 20% 1	354
	21st to end	Night	23% 5% 19% 32% 18% 3	389
June	1st to 10th	Night	21% 6% 21% 36% 14% 2	360
	11th to 20th	Night	22% 4 20% 33% 20% 1	360
	21st to end	Night	11% 3 21% 39% 25% 3	360
July	1st to 10th	Night	13% 2 15% 43% 25% 1	350
	11th to 20th	Night	12% 3 20% 45% 19% 1	348
	21st to end	Night	10% 3 15% 43% 27% 3	394
August	1st to 10th	Night	11% 3 19% 38% 25% 4	358
	11th to 20th	Night	12% 4 16% 40% 26% 2	508
	21st to end	Night	11% 3 20% 41% 24% 1	594
September	1st to 10th	Night	12% 3 22% 42% 19% 1	562
	11th to 20th	Night	16% 4 21% 41% 18% 1	720
	21st to end	Night	12% 5% 26% 42% 15% 1	720
October	1st to 10th	Night	15% 2 30% 36% 15% 2	720
	11th to 20th	Night	14% 4 34% 32% 15% 2	720
	21st to end	Night	11% 8% 34% 36% 11% 1	795
November	1st to 10th	Night	16% 6% 34% 33% 10% 1	925
	11th to 20th	Night	12% 9% 35% 33% 9% 3	950
	21st to end	Night	9% 5% 39% 35% 11% 1	950
December	1st to 10th	Night	12% 8% 32% 32% 14% 2	950
	11th to 20th	Night	11% 6% 34% 35% 12% 2	950
	21st to end	Night	12% 4 34% 33% 15% 2	1045

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