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 2024-11-25.

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	9% 9% 3 8% 5% 5% 5% 4 6% 8% 37%	105821
	Night	8% 10% 4 9% 6% 5% 5% 4 6% 8% 34%	102224
Transparency	Day	44% 7% 16% 24% 9% 1	105562
	Night	46% 7% 15% 22% 9% 1	102129
Seeing	Day	13% 6% 24% 31% 20% 6%	15529
	Night	13% 6% 28% 36% 15% 2	24578

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	5% 12% 5% 12% 9% 6% 4 3 5% 8% 30%	2219
	11th to 20th	Day	4 9% 4 10% 7% 6% 7% 6% 10% 8% 29%	2199
	21st to end	Day	5% 12% 5% 9% 7% 5% 5% 4 6% 7% 35%	2643
February	1st to 10th	Day	8% 14% 4 12% 6% 6% 4 3 6% 10% 26%	1520
	11th to 20th	Day	7% 12% 5% 13% 7% 6% 6% 5% 6% 6% 27%	1661
	21st to end	Day	5% 11% 5% 12% 7% 6% 7% 5% 7% 8% 26%	1455
March	1st to 10th	Day	5% 12% 5% 13% 8% 7% 6% 5% 6% 7% 26%	3155
	11th to 20th	Day	6% 12% 3 7% 5% 4 4 4 6% 9% 41%	3489
	21st to end	Day	7% 15% 6% 17% 6% 5% 4 3 5% 6% 25%	3825
April	1st to 10th	Day	9% 12% 3 9% 7% 7% 5% 5% 6% 7% 30%	2379
	11th to 20th	Day	12% 10% 4 10% 6% 5% 5% 4 6% 6% 31%	2440
	21st to end	Day	13% 10% 3 7% 6% 5% 5% 4 7% 10% 31%	2470
May	1st to 10th	Day	16% 11% 3 10% 5% 4 5% 4 6% 6% 29%	4509
	11th to 20th	Day	11% 11% 3 8% 5% 6% 6% 5% 6% 8% 30%	4694
	21st to end	Day	13% 8% 4 10% 6% 6% 5% 4 7% 7% 29%	5161
June	1st to 10th	Day	16% 7% 3 6% 6% 4 5% 4 8% 9% 32%	2850
	11th to 20th	Day	19% 9% 3 8% 7% 5% 5% 4 7% 8% 25%	2850
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 5% 7% 9% 40%	2850
July	1st to 10th	Day	8% 4 2 5% 4 4 4 4 7% 8% 50%	4740
	11th to 20th	Day	10% 4 2 5% 4 4 5% 4 7% 9% 49%	4740
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 5% 10% 50%	5138
August	1st to 10th	Day	11% 5% 2 6% 5% 4 5% 4 6% 7% 46%	4500
	11th to 20th	Day	7% 5% 2 6% 4 5% 5% 5% 9% 11% 42%	4066
	21st to end	Day	10% 4 2 5% 4 4 5% 4 6% 8% 47%	4521
September	1st to 10th	Day	12% 5% 2 5% 5% 4 5% 4 6% 6% 45%	2403
	11th to 20th	Day	15% 8% 2 6% 4 3 3 3 5% 7% 43%	2090
	21st to end	Day	9% 7% 2 5% 4 4 4 3 7% 9% 45%	2090
October	1st to 10th	Day	8% 8% 3 7% 5% 5% 5% 3 6% 6% 44%	3271
	11th to 20th	Day	7% 7% 3 7% 5% 5% 4 4 7% 10% 40%	2950
	21st to end	Day	8% 9% 3 8% 5% 5% 5% 4 6% 7% 39%	3053
November	1st to 10th	Day	9% 16% 6% 10% 8% 4 6% 3 5% 7% 25%	1568
	11th to 20th	Day	6% 13% 5% 13% 5% 5% 5% 4 6% 8% 30%	1510
	21st to end	Day	7% 10% 4 13% 7% 5% 5% 5% 6% 7% 32%	1358
December	1st to 10th	Day	8% 12% 4 13% 10% 8% 6% 4 6% 6% 24%	1330
	11th to 20th	Day	6% 10% 5% 14% 6% 7% 7% 5% 7% 7% 26%	1682
	21st to end	Day	4 8% 3 9% 6% 4 4 4 6% 8% 44%	2442
January	1st to 10th	Night	4 12% 5% 13% 7% 6% 6% 5% 7% 8% 27%	4726
	11th to 20th	Night	4 9% 4 10% 9% 6% 6% 5% 6% 7% 32%	4699
	21st to end	Night	6% 13% 5% 11% 6% 4 5% 4 6% 8% 34%	5044
February	1st to 10th	Night	6% 11% 6% 11% 8% 7% 5% 4 6% 7% 28%	2660
	11th to 20th	Night	6% 14% 5% 9% 7% 6% 6% 6% 7% 7% 28%	2405
	21st to end	Night	5% 11% 5% 9% 7% 6% 6% 5% 6% 9% 31%	1998
March	1st to 10th	Night	4 10% 5% 16% 7% 6% 5% 4 8% 9% 25%	3719
	11th to 20th	Night	5% 11% 3 8% 6% 6% 5% 5% 6% 9% 37%	3490
	21st to end	Night	6% 13% 7% 17% 8% 6% 6% 4 6% 7% 20%	3828
April	1st to 10th	Night	8% 12% 3 10% 6% 5% 5% 4 7% 8% 32%	1799
	11th to 20th	Night	11% 11% 5% 10% 5% 6% 5% 5% 7% 8% 29%	1691
	21st to end	Night	13% 10% 4 7% 6% 5% 5% 3 7% 8% 33%	1710
May	1st to 10th	Night	24% 12% 4 7% 4 5% 4 3 5% 5% 28%	2454
	11th to 20th	Night	11% 10% 4 10% 6% 6% 5% 5% 7% 8% 29%	2199
	21st to end	Night	16% 9% 3 9% 7% 5% 6% 5% 7% 8% 24%	2414
June	1st to 10th	Night	16% 7% 2 8% 5% 6% 5% 6% 8% 7% 29%	1330
	11th to 20th	Night	16% 9% 4 9% 6% 5% 6% 4 6% 7% 27%	1330
	21st to end	Night	9% 4 3 6% 4 6% 6% 5% 10% 9% 38%	1330
July	1st to 10th	Night	9% 6% 2 7% 5% 4 5% 4 6% 7% 45%	2220
	11th to 20th	Night	8% 4 2 5% 5% 4 5% 4 7% 11% 46%	2220
	21st to end	Night	8% 6% 2 5% 3 3 5% 4 7% 10% 46%	2414
August	1st to 10th	Night	13% 6% 2 5% 3 4 4 4 5% 9% 44%	2428
	11th to 20th	Night	8% 6% 2 7% 4 5% 5% 5% 8% 8% 42%	2772
	21st to end	Night	10% 5% 3 6% 5% 5% 5% 4 7% 8% 43%	3146
September	1st to 10th	Night	11% 5% 3 7% 5% 4 5% 3 6% 7% 44%	1774
	11th to 20th	Night	15% 7% 2 6% 4 3 4 3 5% 7% 45%	2090
	21st to end	Night	9% 7% 3 6% 5% 4 4 4 6% 9% 44%	2090
October	1st to 10th	Night	9% 7% 3 7% 5% 5% 5% 4 6% 8% 42%	3702
	11th to 20th	Night	7% 8% 3 6% 4 4 5% 4 7% 9% 40%	3962
	21st to end	Night	7% 11% 3 8% 6% 6% 6% 5% 6% 8% 35%	4473
November	1st to 10th	Night	10% 15% 5% 8% 5% 4 5% 4 6% 8% 29%	2730
	11th to 20th	Night	7% 13% 5% 10% 6% 7% 5% 4 6% 8% 29%	2886
	21st to end	Night	6% 12% 4 11% 8% 5% 6% 4 6% 8% 30%	2917
December	1st to 10th	Night	8% 13% 5% 11% 8% 6% 5% 4 6% 7% 28%	2850
	11th to 20th	Night	5% 11% 4 12% 8% 5% 6% 4 6% 9% 28%	3510
	21st to end	Night	4 8% 4 8% 6% 5% 5% 4 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	52% 6% 11% 21% 9%	2219
	11th to 20th	Day	45% 6% 14% 12% 20% 3	2220
	21st to end	Day	46% 7% 16% 24% 6%	2643
February	1st to 10th	Day	54% 6% 13% 16% 10% 1	1520
	11th to 20th	Day	54% 7% 12% 16% 10% 1	1670
	21st to end	Day	52% 7% 13% 18% 9%	1455
March	1st to 10th	Day	56% 7% 13% 16% 8%	3155
	11th to 20th	Day	38% 8% 19% 21% 14%	3490
	21st to end	Day	59% 7% 11% 19% 4	3825
April	1st to 10th	Day	50% 8% 15% 17% 9% 1	2379
	11th to 20th	Day	51% 6% 13% 20% 10%	2440
	21st to end	Day	47% 8% 14% 21% 8% 2	2470
May	1st to 10th	Day	54% 6% 10% 24% 6%	4509
	11th to 20th	Day	49% 9% 11% 22% 9%	4698
	21st to end	Day	49% 9% 16% 17% 8% 1	5162
June	1st to 10th	Day	45% 9% 14% 23% 8% 1	2850
	11th to 20th	Day	54% 9% 14% 18% 4 1	2850
	21st to end	Day	38% 10% 24% 22% 7% 1	2850
July	1st to 10th	Day	30% 7% 16% 29% 15% 2	4666
	11th to 20th	Day	32% 8% 16% 32% 12%	4659
	21st to end	Day	31% 7% 17% 29% 15% 1	4976
August	1st to 10th	Day	37% 8% 16% 34% 5%	4482
	11th to 20th	Day	32% 8% 25% 28% 6%	4105
	21st to end	Day	33% 7% 24% 29% 7%	4520
September	1st to 10th	Day	37% 7% 18% 26% 9% 3	2403
	11th to 20th	Day	42% 5% 16% 29% 8% 1	2090
	21st to end	Day	35% 8% 18% 26% 11% 3	2090
October	1st to 10th	Day	40% 5% 20% 29% 6%	3271
	11th to 20th	Day	39% 6% 16% 28% 11% 1	2950
	21st to end	Day	43% 6% 13% 32% 6%	3053
November	1st to 10th	Day	58% 6% 11% 17% 7% 1	1568
	11th to 20th	Day	52% 7% 15% 19% 7%	1510
	21st to end	Day	49% 8% 17% 18% 6% 1	1358
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	52% 7% 14% 19% 6% 2	4726
	11th to 20th	Night	50% 5% 13% 15% 14% 3	4740
	21st to end	Night	48% 6% 15% 23% 7% 1	5044
February	1st to 10th	Night	53% 6% 12% 19% 9% 1	2660
	11th to 20th	Night	51% 8% 13% 16% 11% 1	2406
	21st to end	Night	46% 7% 13% 21% 11% 1	1998
March	1st to 10th	Night	52% 8% 13% 20% 7%	3719
	11th to 20th	Night	42% 6% 19% 20% 11% 1	3490
	21st to end	Night	59% 10% 11% 13% 7%	3828
April	1st to 10th	Night	47% 8% 14% 19% 12% 1	1799
	11th to 20th	Night	49% 7% 12% 20% 9% 2	1691
	21st to end	Night	46% 7% 13% 22% 10% 2	1710
May	1st to 10th	Night	58% 5% 8% 21% 7% 1	2454
	11th to 20th	Night	47% 8% 14% 22% 8% 1	2199
	21st to end	Night	52% 11% 14% 15% 7% 1	2414
June	1st to 10th	Night	48% 10% 13% 19% 8% 1	1330
	11th to 20th	Night	55% 8% 13% 18% 6% 1	1330
	21st to end	Night	37% 11% 21% 24% 7% 1	1330
July	1st to 10th	Night	36% 8% 17% 20% 16% 1	2185
	11th to 20th	Night	31% 8% 15% 34% 9% 2	2178
	21st to end	Night	32% 7% 21% 28% 12% 1	2337
August	1st to 10th	Night	37% 7% 17% 33% 5%	2421
	11th to 20th	Night	36% 8% 21% 27% 7% 1	2799
	21st to end	Night	36% 7% 20% 29% 6% 1	3146
September	1st to 10th	Night	38% 8% 14% 24% 13% 4	1774
	11th to 20th	Night	39% 7% 13% 29% 10% 3	2090
	21st to end	Night	36% 7% 13% 26% 14% 3	2090
October	1st to 10th	Night	40% 5% 19% 26% 10% 1	3702
	11th to 20th	Night	39% 6% 14% 31% 9% 1	3962
	21st to end	Night	45% 7% 16% 27% 5% 1	4473
November	1st to 10th	Night	51% 7% 13% 21% 7% 1	2730
	11th to 20th	Night	52% 7% 13% 19% 8% 1	2886
	21st to end	Night	50% 8% 15% 18% 7% 1	2917
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% 38% 19% 4	180
	21st to end	Day	12% 7% 31% 28% 14% 8%	198
February	1st to 10th	Day	16% 6% 29% 32% 13% 4	180
	11th to 20th	Day	12% 5% 30% 32% 16% 4	268
	21st to end	Day	7% 5% 29% 35% 18% 6%	267
March	1st to 10th	Day	12% 8% 31% 28% 19% 3	460
	11th to 20th	Day	11% 3 32% 33% 14% 7%	460
	21st to end	Day	14% 7% 28% 32% 14% 5%	506
April	1st to 10th	Day	12% 12% 30% 29% 13% 3	460
	11th to 20th	Day	15% 8% 24% 30% 18% 5%	452
	21st to end	Day	17% 7% 27% 31% 15% 3	460
May	1st to 10th	Day	16% 8% 23% 29% 19% 6%	605
	11th to 20th	Day	10% 8% 22% 33% 20% 6%	675
	21st to end	Day	17% 5% 19% 29% 21% 9%	734
June	1st to 10th	Day	18% 7% 23% 32% 16% 4	680
	11th to 20th	Day	19% 6% 25% 26% 18% 5%	680
	21st to end	Day	12% 4 22% 30% 24% 9%	680
July	1st to 10th	Day	12% 4 15% 32% 28% 10%	671
	11th to 20th	Day	14% 5% 17% 32% 25% 8%	668
	21st to end	Day	8% 5% 17% 31% 30% 10%	739
August	1st to 10th	Day	11% 2 20% 30% 25% 11%	547
	11th to 20th	Day	10% 4 20% 29% 30% 8%	477
	21st to end	Day	11% 6% 17% 30% 25% 10%	539
September	1st to 10th	Day	12% 8% 25% 27% 21% 7%	490
	11th to 20th	Day	18% 5% 26% 27% 20% 5%	490
	21st to end	Day	13% 11% 26% 30% 16% 4	490
October	1st to 10th	Day	17% 6% 29% 25% 18% 6%	362
	11th to 20th	Day	10% 9% 28% 34% 16% 3	300
	21st to end	Day	13% 7% 34% 30% 14% 3	330
November	1st to 10th	Day	16% 6% 30% 31% 13% 4	300
	11th to 20th	Day	12% 7% 36% 31% 12% 2	255
	21st to end	Day	10% 7% 30% 31% 16% 5%	188
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	11% 8% 31% 35% 13% 2	950
	21st to end	Night	14% 10% 31% 32% 11% 2	940
February	1st to 10th	Night	9% 8% 26% 36% 18% 3	760
	11th to 20th	Night	12% 6% 33% 34% 14% 1	744
	21st to end	Night	10% 5% 25% 38% 19% 4	628
March	1st to 10th	Night	9% 6% 28% 39% 17% 2	760
	11th to 20th	Night	11% 4 32% 36% 14% 3	760
	21st to end	Night	15% 3 27% 37% 15% 2	836
April	1st to 10th	Night	9% 6% 30% 35% 17% 4	654
	11th to 20th	Night	14% 7% 31% 37% 10% 1	563
	21st to end	Night	18% 6% 25% 36% 14%	570
May	1st to 10th	Night	17% 5% 25% 38% 13% 2	475
	11th to 20th	Night	13% 5% 24% 37% 19% 1	374
	21st to end	Night	22% 5% 19% 33% 18% 3	411
June	1st to 10th	Night	20% 6% 23% 35% 14% 2	380
	11th to 20th	Night	21% 3 22% 33% 19% 1	380
	21st to end	Night	11% 3 20% 38% 25% 2	380
July	1st to 10th	Night	13% 2 15% 43% 26% 1	370
	11th to 20th	Night	11% 2 20% 45% 20% 1	368
	21st to end	Night	11% 4 15% 42% 27% 2	416
August	1st to 10th	Night	11% 2 19% 37% 26% 4	378
	11th to 20th	Night	11% 4 16% 41% 26% 2	537
	21st to end	Night	11% 4 20% 41% 24%	627
September	1st to 10th	Night	12% 3 21% 42% 20% 1	594
	11th to 20th	Night	16% 3 20% 41% 18% 1	760
	21st to end	Night	12% 5% 27% 42% 14% 1	760
October	1st to 10th	Night	15% 3 29% 36% 14% 2	760
	11th to 20th	Night	14% 4 33% 33% 14% 1	760
	21st to end	Night	11% 8% 33% 36% 11% 1	840
November	1st to 10th	Night	16% 6% 34% 34% 10% 1	975
	11th to 20th	Night	12% 8% 35% 33% 9% 3	1000
	21st to end	Night	10% 5% 38% 34% 11% 2	973
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

Page generated at 2024-11-22 06:02:27. Version ac07

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